National Library of Medicine (NLM)


The National Library of Medicine plays a pivotal role in translating biomedical research into practice. As the world’s largest biomedical library, NLM creates and hosts major resources, tools, and services for literature, data, standards, and more, sending more than 100 terabytes of data to nearly five million users and receiving more than ten terabytes of data from more than 3,000 users every weekday.

Scientists, health professionals, and the public in the United States and around the world search the Library's online information resources billions of times each year.In addition, NLM leads research and research training in biomedical informatics, information science, and data science. It conducts intramural research and training it is own laboratories and supports extramural research and training in institutions across the United States.

NLM is part of the National Institutes of Health (NIH), U.S. Department of Health and Human Services, in Bethesda, Maryland, tracing its roots to the founding of the library of the U.S. Army Surgeon General in 1836.

NLM’s Strategic Plan for 2017–2027 envisions NLM as a platform for biomedical discovery and data-powered health by 1) innovating, building, and sustaining an open ecosystem for health information, biomedical data, and scientific scholarship, 2) optimizing user experience and use of our data, literature, and information resources, and 3) assuring a diverse and growing data-savvy biomedical workforce and data-ready users of NLM resources. NLM facilitates open science and scholarship by making digital (and non-digital) research objects findable, accessible, interoperable, reusable, attributable, and sustainable. The practice, products, and processes of data science and open science permeate all of NLM, throughout both its research and service portfolios.

More specifically, NLM carries out its mission of enabling biomedical research, supporting health care and public health, and promoting healthy behavior by—

  • Acquiring, organizing, preserving, and providing free online access to scholarly biomedical literature from around the world.
  • Providing access to biomedical and health information across the country in partnership with the over 6,400 members of the National Network of Libraries of Medicine
  • Serving as a leading global resource for building, curating, and providing sophisticated access to molecular biology, genomic, clinical trial, toxicological, environmental health and other types of biomedical data, including those from high-profile, trans-NIH initiatives.
  • Conducting research and development on biomedical communications systems, methods, technologies, and networks and information dissemination and utilization among health professionals, patients, and the general public.
  • Funding advanced biomedical informatics and data science research and serving as the primary supporter of pre- and post-doctoral research training in biomedical informatics and data science at 18 U.S. universities.

Important Events in NLM History

1836—Library of the Office of the Surgeon General of the Army (the present National Library of Medicine) established.

1865—John Shaw Billings, M.D., appointed to supervise Surgeon General's Library, which he developed into a national resource of biomedical literature. He served as director until 1895.

1879—First volume of Index Medicus, the first attempt to identify and code the medical literature, published.

1880—First volume of Index-Catalogue, a multi-part printed bibliography, published.

1922—Library of the Office of the Surgeon General (Army) renamed Army Medical Library.

1952—Army Medical Library renamed Armed Forces Medical Library.

1956—Act of Congress moves Armed Forces Medical Library to U.S. Public Health Service (PHS) and renames it the National Library of Medicine.

1961—New National Library of Medicine building, #38 (at 8600 Rockville Pike, Bethesda, Maryland, on the NIH campus), dedicated.

1964—Medical Literature Analysis and Retrieval System (MEDLARS), a computer-based system for medical professionals to retrieve biomedical information, becomes operational at NLM.

1965—Medical Library Assistance Act gives NLM responsibility of helping the nation's medical libraries through a grant program and creates the Regional Medical Library Network (now the National Network of Libraries of Medicine).

1967—Toxicology Information Program established at NLM in response to recommendations of the President's science advisory committee.

1968—NLM becomes a component of NIH. The Lister Hill National Center for Biomedical Communications, NLM's research and development component, created by Congress.

1971—MEDLINE ("MEDLARS Online") initiated to provide online access to a subset of references in the MEDLARS database.

1972TOXLINE, an online bibliographic service covering pharmacology and toxicology, becomes operational.

1980—NLM's Lister Hill National Center for Biomedical Communications building, #38A, is dedicated. Adjacent to the Library, it houses NLM's research and development components.

1986—Grateful Med—user-friendly software for accessing MEDLARS—is introduced to the health community.

1988—The National Center for Biotechnology Information (NCBI) is established at NLM by Congress as a national resource for molecular biology information.

1992—NCBI assumes responsibility for GenBank and US participation in the International Nucleotide Sequence Consortium.

1993National Information Center on Health Services Research and Health Care Technology established at NLM by Congress as a national resource for health services research and evidence-based practice guidelines.

1993—NLM's website ( appears.

1994—The Visible Human Male, a large computer dataset of images based on a cadaver, is introduced. The Visible Human Female appears one year later.

1997—Access to NLM's MEDLINE/PubMed database becomes free via the World Wide Web.

1998MedlinePlus released, providing access to consumer health information., an online resource to give the public easy access to information about research studies, is launched.

2000PubMed Central, a free archive of biomedical and life sciences journal literature, is launched.

2002—NLM launches traveling historical exhibition program with release ofFrankenstein: Penetrating the Secrets of Nature.

2003—NLM releases standard format for electronic archiving and publishing of journal articles—the journal article tagging suite or JATS, which later becomes a national standard.

2004—The Secretary of HHS designates NLM as the HHS Coordinating Body for Clinical Terminology Standards.

2006NIH MedlinePlusmagazine launched to provide Americans with reliable, current health information in a consumer-friendly format. The Spanish-English version, Salud, follows two years later.

2006—dbGaP, the database of genomes and phenomes, launched to provide access genome-wide association studies.

2006—DailyMed makes FDA-approved electronic structured product labels (drug package inserts) available to the public and system developers.

2008—NIH public access policy, requiring deposit in PMC of peer-reviewed articles resulting from NIH-funded research becomes mandatory, as specified in 2008 appropriations law.

2008—Deposit of summary results data in becomes mandatory for selected clinical trials of FDA-regulated drugs and devices, as specified in the FDA Amendments Act of 2007.

2010—MedlinePlus Connect, a service linking patients or providers in electronic health record (EHR) systems to related MedlinePlus information on conditions or medications, released.

2010—Vocabulary standards supported or developed by NLM (LOINC, RxNorm, SNOMED CT) included in rule specifying U.S. certification criteria for electronic health record systems.

2015—AccessGUDID makes medical device information submitted to the FDA available to the public.

2015—Other HHS agencies and other Federal Departments elect to require deposit of publications resulting from their funded research into PMC.

2016—Patricia Flatley Brennan, RN, PhD, becomes the first woman and first nurse appointed to head the Library.

2017—HHS issues final rule for registration and reporting of summary results of clinical trials at NIH issues policy extending the requirements to all NIH-funded clinical trials.

NLM Legislative Chronology

August 3, 1956—An amendment to Title III of the Public Health Service Act, the National Library of Medicine Act, places the Armed Forces Medical Library under the PHS, and renames it the National Library of Medicine (Public Law 84-941).

October 22, 1965—The Medical Library Assistance Act of 1965 (Public Law 89-291) authorizes NLM's extramural programs of grant assistance to help expand and improve the nation's medical library and health communications resources, technology, and professional staff for service to the health community.

August 3, 1968—Public Law 90-456 authorizes the designation of the Lister Hill National Center for Biomedical Communications.

November 4, 1988—Health Omnibus Programs Extension Act (Public Law 100-607) authorizes establishment of the National Center for Biotechnology Information at NLM.

June 10, 1993—National Institutes of Health Revitalization Act (Public Law 103-43) authorizes establishment of the National Information Center on Health Services Research and Health Care Technology at NLM.

November 21, 1997—The Food and Drug Administration Modernization Act (Public Law 105-115) calls for the creation of a centralized, consumer-friendly online listing of clinical trials, which would become

September 27, 2007—The Food and Drug Administration Amendments Act (Public Law 111-85) extends the scope of clinical trials to be registered at and expands the data bank to include summary results of completed clinical trials.

Biographical Sketch of NLM Director Patricia Flatley Brennan, RN, PhD

portrait of Patricia Flatley Brennan

Patricia Flatley Brennan, RN, PhD, is the Director of the National Library of Medicine, the world’s largest biomedical library and the producer of digital information services used by scientists, health professionals and members of the public worldwide.

Since assuming the directorship in August 2016, Dr. Brennan has positioned the Library to be the hub of data science at NIH and a national and international leader in the field. She spearheaded the development of a strategic plan that envisions NLM as a platform for biomedical discovery and data-powered health. Leveraging NLM’s data and information resources, intramural research, and extramural research and training programs, Dr. Brennan aims for NLM to accelerate data driven discovery and health, engage with new users in new ways and develop the workforce for a data-driven future.

Her professional accomplishments reflect her background, which unites engineering, information technology, and clinical care to improve the public health and ensure the best possible experience in patient care.

Dr. Brennan came to NIH from the University of Wisconsin-Madison, where she was the Lillian L. Moehlman Bascom Professor at the School of Nursing and College of Engineering. She also led the Living Environments Laboratory at the Wisconsin Institutes for Discovery, which develops effective visualization of high dimensional data.

She received a Master of Science in nursing from the University of Pennsylvania and a PhD in industrial engineering from the University of Wisconsin-Madison. Following clinical practice in critical care nursing and psychiatric nursing, Dr. Brennan held academic positions at Marquette University, Milwaukee; Case Western Reserve University, Cleveland; and the University of Wisconsin-Madison.

A past president of the American Medical Informatics Association, Dr. Brennan was elected to the Institute of Medicine of the National Academy of Sciences (now the National Academy of Medicine) in 2001. She is a fellow of the American Academy of Nursing, the American College of Medical Informatics and the New York Academy of Medicine.

A selected bibliography is available.You can learn more about Dr. Brennan through her blog Musings from the Mezzanine and her Twitter account: @NLMdirector.

NLM Directors


In Office from


Leon Lloyd Gardner



Joseph Hamilton McNinch



Frank Bradway Rogers



Martin Marc Cummings



Donald A.B. Lindberg


March 31, 2015

Betsy L. Humphreys (Acting)

April 1, 2015

August 2016

Patricia Flatley Brennan

August 2016 Present

Major Divisions

Division of Extramural Programs

NLM’s Extramural Programs Division offers grant support for research projects and research training in biomedical informatics and data science. Biomedical informatics and data science research develop methods and approaches to improve the capture, integration, management, analysis, visualization, retrieval, and use of biomedical and behavioral information and data relating to human health. The Extramural Programs Division provides research support for both basic and applied research in these and related areas.

To expand the biomedical workforce in the area of biomedical informatics and data science, NLM supports training in biomedical informatics at educational institutions throughout the U.S. These programs offer pre-doctoral and post-doctoral training for research careers in health care informatics, biomedical data science, translational informatics, clinical research informatics, public health informatics, and related areas. Career development awards assist recent PhDs and MDs who are establishing research careers in these fields. In addition, a special collaborative program with other NIH Institutes and Centers supports bringing informationists (e.g., librarians and other information specialists) into NIH-funded research teams to enhance data management and sharing.

Grants are also made to U.S. small businesses that seek to undertake informatics research and development leading to commercialization. Critical research areas include representation of medical knowledge in computers; organization and retrieval issues for image databases; enhancement of human intellectual capacities through virtual reality, dynamic modeling, artificial intelligence, and machine learning; medical decision-making; linguistic analyses of medical languages and nomenclatures; investigations of topics relevant to health information or library science; biotechnology informatics issues; and informatics for disaster management.

The Extramural Programs Division has two unique programs to support resource projects in the history and philosophy of medicine and public health and for developing information resources to help reduce health disparities.

All active grant programs of NLM, lists of recent awardees, and contact information for grant staff are provided at

Division of Library Operations (LO)

The Division of Library Operations ensures access to the published record of the biomedical sciences and the health professions. LO acquires, organizes, and preserves NLM’s comprehensive archival collection of biomedical literature currently numbering over 30 million items, print and digital combined; creates and disseminates controlled vocabularies, including MeSH, UMLS, and RxNorm, and a library classification scheme. Library Operations produces authoritative indexing and cataloging records; and builds and distributes bibliographic, directory, and full -text databases including the databases MEDLINE through PubMed, MedlinePlus, MedlinePlus en español, and its electronic health record compatible version, MedlinePlus Connect, and DailyMed. Library Operations is home to the NIH Common Data Element (CDE) Repository, part of an NIH-wide initiative to encourage using common data elements in clinical research and patient registries. Library Operations provides national backup document delivery through several tools, primarily through the NLM system DOCLINE, and reference service, and research assistance; and helps people effectively use NLM products and services. Library Operations coordinates the National Network of Libraries of Medicine to equalize access to health information across the United States. These essential services support NLM’s outreach to health professionals, patients, families and the public, as well as focused programs in AIDS information, molecular biology, health services research, public health, toxicology, environmental health, and disaster planning.

Library Operations also develops and mounts historical exhibitions; produces and manages a travelling exhibition program; carries out an active research program in the history of medicine and public health; collaborates with other NLM program areas to develop, enhance, and publicize NLM products and services; conducts research related to current operations; directs and supports training and recruiting programs for health sciences librarians; and manages the development and dissemination of national health data terminology standards.

NIH MedlinePlus magazine is printed four times each year andSaludmagazine in English and Spanish is printed annually. Online content is updated throughout the year.

Lister Hill National Center for Biomedical Communications (LHNCBC)

Congress established the Lister Hill Center for Biomedical Communications in 1968 to improve communication about health education, research, and practice. Today, LHNCBC develops advanced information resources and software tools for biomedical research used by health IT professionals, health care providers, and consumers. Current research focuses on high-speed access to biomedical information, the processing and dissemination of clinical imagery, medical language processing and data standards, intelligent database systems, multimedia visualization, knowledge management, data mining, and machine-assisted indexing.

Specifically, LHNCBC imaging research includes Open-i®, a hybrid system combining text- and image-based searching, and SimpleITK, an interface for using open source ITK tools for image segmentation and registration. Image analysis combined with deep learning is applied to several types of clinical images: chest x-rays (CXR), uterine cervix images, and microscopic cell images from blood smears. Examples include the detection and counting of parasitic cells in blood smears to automatically screen for malaria and the implementation of these algorithms in smartphones for validation in the field (MalariaScreener); the detection of lung diseases (e.g., tuberculosis) and cardiomegaly from CXR; and the detection and staging of cervical cancer from uterine cervix photographs and histology images.

LHNCBC leads the development, enhancement, and adoption of clinical vocabulary standards. To facilitate interoperability between producers and receivers of health care data, LHNCBC created tools and content for all of the major Meaningful Use coding systems: LOINC, RxNorm and SNOMED CT, as well as for UCUM, the computable code system for units of measure. LHNCBC studies involved several large clinical datasets including the CMS Virtual Research Data Center, OHDSI, and the Indiana 10K dataset.

Based on its research regarding normalizing unstructured data and integrating heterogeneous datasets, the newborn screening message and code standard was developed within LHNCBC as an HL7 V2 message with a specific menu of LOINC terms for reporting the results of metabolic screening tests. In collaboration with outside researchers, LHNCBC actively contributed to HL7 Clinical Genomics and HL7 FHIR, a recently introduced clinical genomics reporting standard.

LHNCBC also developed many projects related to Natural Language Processing and biomedical terminologies. For example, NLM Scrubber uses deterministic and probabilistic pattern recognition to flag personal health information in clinical documents. Another project extracts drug safety information from labels and structures it for clinical decision support. The NLM Medical Text Indexer produces indexing recommendations and assigns MeSH headings to appropriate text. The Consumer Health Question Answering systems provides information from reliable sources to answer health related questions.

With diverse backgrounds in medicine, computer science, linguistics, engineering, education, and library and cognitive sciences, the LHNCBC staff is committed to its leadership position in biomedical research and development. The staff often collaborates with public and private sector partners and regularly publishes results in medical informatics, computer and information sciences, and engineering communities. From an educational perspective, the LHNCBC Biomedical Informatics Training Program has been attracting and encouraging talented learners for over 20 years.

National Center for Biotechnology Information (NCBI)

Congress established NCBI in 1988 as a division of the National Library of Medicine and a national resource for molecular biology information. Since then, NCBI has become a leading source for public biomedical databases, software tools for analyzing molecular and genomic data, and research in computational biology.

NCBI creates and maintains over 40 databases for the medical and scientific communities as well as the general public; these include literature, molecular, and genomic databases. NCBI’s core literature database is PubMed, which provides abstracts and citations for millions of articles from thousands of biomedical journals. PubMed records include links to full-text versions of the articles (when available) from NCBI’s PubMed Central (PMC) electronic archive and from journal websites, as well as links to related information from other NCBI sites, such as the genomic and molecular databases.

Some of NCBI’s core genomic resources are GenBank, an annotated collection of all publicly available DNA sequences; RefSeq, a curated collection of DNA, RNA, and protein sequences; dbSNP, a database of short genetic variations (areas of the genome that have been found to vary among humans); dbGaP, a database that connects genotype and phenotype data from genome-wide association studies (GWAS) and other studies; and the Pathogen Detection resource, which integrates sequence data for bacterial pathogens obtained from food, the environment, and human patients to facilitate active, real-time surveillance of pathogens and foodborne disease. Additional databases include chemical structures and their biological activities, protein sequences, protein structure, chromosomal aberrations in cancer, genes and gene expression, and taxonomy.

NCBI also has a multi-disciplinary research group composed of molecular biologists, biochemists, computer scientists, mathematicians, research physicians, and structural biologists concentrating on basic and applied research in computational molecular biology. Together they study fundamental biomedical problems, including comparative genomics, proteomics, molecular evolution, and disease. These investigators not only make important contributions to basic science but also serve as a wellspring of new methods for applied research activities, including enhancements to NCBI’s publicly available databases and software tools.

Office of Computer & Communications Systems (OCCS)

OCCS provides information technology services and technical advice to support the research and management programs offered through NLM. OCCS manages and operates the NLM network backbone, connections to the Internet and Internet2 networks, internal computer networks within NLM, NLM’s onsite and offsite data center facilities, platforms for enterprise compute and storage, platforms for end-user computation, and mobile user and remote access technologies.

OCCS provides customer support, training, and documentation for computer and network users. In addition, OCCS develops standards and guidance for managing and using information technology at NLM in accordance with industry best practices and applicable federal government mandates. OCCS provides oversight of all information security programs at NLM and ensures that NLM information systems comply with federal information security standards.

OCCS develops and operates IT services and software applications that support the Library’s mission. OCCS develops applications both for internal and public use—with specific expertise in developing software applications that use standardized medical terminology.

As the chief information officer of NLM, the director of OCCS approves acquisitions related to information technology and oversees the governance process for NLM investments in information technology.

This page last reviewed on January 21, 2020