About MEDLINE® and PubMed®: The Resources Guide

MEDLINE® contains journal citations and abstracts for biomedical literature from around the world.
PubMed® provides free access to MEDLINE and links to full text articles when possible.

Search PubMed (including MEDLINE):

The following resources provide detailed information about MEDLINE data and searching PubMed. If you cannot find the information you seek, please contact NLM Customer Support.

NEWS

PubMed New and Noteworthy:
List of changes to PubMed by date, with links to the Technical Bulletin.
NLM Technical Bulletin:
The NLM Technical Bulletin is your main source for detailed information about changes and updates to NLM resources, including MEDLINE and PubMed.
NLM-Announces:
NLM e-mail list for announcing important information and changes to NLM systems including PubMed.

OVERVIEWS

MEDLINE®:
A brief description of MEDLINE, your database of biomedical and life sciences journal citations.
PubMed:
A brief description of PubMed, part of the Entrez retrieval system and your free access to MEDLINE.
MEDLINE, PubMed, and PMC (PubMed Central): How are they different?:
A brief description of MEDLINE, PubMed, and PMC.
MeSH®:
To help you understand NLM's controlled vocabulary thesaurus. Helpful for searching NLM's databases. See also Medical Subject Headings (MeSH®)in MEDLINE®/PubMed®: A Tutorial and Branching Out: The MeSH Vocabulary (instructional video).
Indexing FAQ:
How indexing is done at NLM, and information on becoming an indexer.
Special Collaborative Arrangements:
An explanation of NLM's special collaborative arrangements for selecting publications.

JOURNALS

MEDLINE Journal Selection:
How journals are selected for the MEDLINE database. See also the FAQ: Journal Selection for MEDLINE Indexing at NLM.
- Journals Recently Accepted by NLM for Inclusion in MEDLINE:
  Those titles recently accepted by the Literature Selection Technical Review Committee (LSTRC).
- MEDLINE Selection Statistics
  Statistics on journal titles reviewed and selected by the Literature Selection Technical Review Committee (LSTRC) by date, country, and format.
List of MEDLINE Journals:
How can I find the list of journals indexed in MEDLINE?
- List of Journals Indexed for MEDLINE:
  A list of currently indexed titles, dynamically generated from the NLM Catalog.
- List of Serials Indexed for Online Users:
  A list of titles formerly and currently indexed in MEDLINE.
List of Journals in PubMed: How can I find the list of journals included in PubMed?
- Journals regularly added to PubMed
  A list of currently indexed MEDLINE journals and journals currently being added to PubMed Central (PMC), dynamically generated from the NLM Catalog. See the PMC Journal List for more information.
- Journals cited, even once, in PubMed
  This list includes MEDLINE and non-MEDLINE titles, including journals whose content is deposited in PMC (PubMed Central) to satisfy public access requirements.
Journal and Citation Subsets:
The table of subset codes assigned to MEDLINE citations. See also Abridged Index Medicus (AIM or "Core Clinical") Journal Titles.
Journal Subject Terms:
Subject Terms are assigned by NLM at the journal level to describe each MEDLINE journal's overall scope.
Construction of National Library of Medicine Title Abbreviations
The rules currently used by NLM to construct title abbreviations for journals indexed in PubMed.
MEDLINE Policy on Indexing Electronic Journals:
NLM policy for indexing, access, and preservation of articles from electronic journals.
- MEDLINE Journals Indexed from the Online Version:
  A list of journals indexed from the online version, with additional information on searching for online journals with LocatorPlus.
Ceased Abstracting and Indexing Publications Containing MEDLINE Citations:
Details about the MEDLINE and non-MEDLINE content of the Hospital Literature Index, the Hospital and Health Administration Index, the Index to Dental Literature, and the International Nursing Index.

DATA STRUCTURE & CONTENT

MEDLINE/PubMed Detailed Field/Data Element Descriptions
Descriptions of the fields in MEDLINE/PubMed records, with detailed historical information, when available.
MeSH Subheadings Table (from PubMed Help):
The MeSH subheadings and their abbreviations. See also the MeSH Qualifiers (subheadings) Hierarchies.
PubMed Publication Types (from PubMed Help):
The publication types used in MEDLINE/PubMed. See also the Publication Characteristics (Publication Types) Scope Notes for definitions of publication types used in all NLM databases.
Languages in MEDLINE/PubMed:
A list of language codes and translations used in MEDLINE/PubMed.
PubMed Citation Status Subsets (from PubMed Help):
A list of status designations for PubMed records.
Journal and Citation Subsets:
The table of subset codes assigned to MEDLINE citations. See also Abridged Index Medicus (AIM or "Core Clinical") Journal Titles.
Grant Number Information Found in the GR Field:
The abbreviation, acronym and name for Institutes and Grants found in the ID field in MEDLINE.
Structured Abstracts:
A description of structured abstracts and how they are formatted for MEDLINE.
PubMed Character Conversions:
How special characters are translated in PubMed.
Code Designations for Greek Characters in the Gene Symbol Field:
How Greek characters are represented in MEDLINE in the Gene Symbol field (used only 1991-1995).
Special Collaborative Arrangements:
An explanation of NLM's special collaborative arrangements for selecting publications.
NLM DTDs:
A DTD (Document Type Definition) defines the building blocks of an XML document. It defines the document structure with a list of allowable elements. These are the DTDs that define NLM's XML data. See also NLM Data Distribution.
MEDLINE Databank Sources:
Names that appear in the DataBankName element in the XML version of the citation and the Secondary Source ID [SI] element in the PubMed MEDLINE display.
Space Life Sciences:
The National Library of Medicine (NLM), in conjunction with the National Aeronautics Space Administration (NASA) SPACELINE Office, provided access to the published literature of space flight and ground-based life sciences research via several resources.

DATA POLICIES

MEDLINE/PubMed Detailed Field/Data Element Descriptions:
Descriptions of the fields in PubMed/MEDLINE records, with detailed historical information, when available. (Note: This document contains policy information for selected data elements.)
Annual MEDLINE/PubMed Year-End Processing Activities:
A description of the annual maintenance, known as year-end processing, done primarily to update MEDLINE citations to the forthcoming year's version of MeSH.
Article Versions and MEDLINE/PubMed Citations
What is and is not a versioned citation from the National Library of Medicine point of view.
Authorship in MEDLINE:
Information on how authorship is reflected in MEDLINE.
Clinical Trial Registry Numbers in MEDLINE/PubMed Records:
Clinical trials information in MEDLINE/PubMed records.
Conflict of Interest Disclosure and Journal Supplements in MEDLINE:
The conditions under which supplements are cited and indexed for MEDLINE.
Construction of National Library of Medicine Title Abbreviations:
How journal title abbreviations are constructed.
Copyright Information & Downloading National Library of Medicine Data:
Guidance for redistribution of MEDLINE/PubMed and other NLM data.
Errata, Retraction, Partial Retraction, Corrected and Republished Articles, Duplicate Publication, Comment, Update, Patient Summary and Republished (Reprinted) Article Policy for MEDLINE:
NLM policies on these publication events.
MEDLINE/PubMed Journal Article Citation Format:
Background on the citation style used in MEDLINE/PubMed. See also Sample References (International Committee of Medical Journal Editors Recommendations for the Conduct, Reporting, Editing and Publication of Scholarly Work in Medical Journals)
Multiple Language Translations of Online Journals and Indexing English Editions of Journals:
MEDLINE/PubMed includes a language field for identifying the languages in which an article is published.
Research Reporting Guidelines and Initiatives: By Organization:
A chart of the major biomedical research reporting guidelines that provide advice for reporting research methods and findings.
Structured Abstracts:
A description of structured abstracts and how they are formatted for MEDLINE.

SEARCHING PUBMED

(See also Help and Training Resources)

PubMed Search Field Descriptions and Tags (from PubMed Help):
A table of all searchable fields in PubMed.
MeSH Qualifiers (Subheading) Hierarchies:
Subheadings arranged in their logical hierarchical groupings, or families. Searching a broader subheading in PubMed will automatically search more specific subheadings.
PubMed Subject Filters:
The search strategies for each PubMed subject filter.
Clinical Queries Filter Table:
Search filters for each clinical and medical genetics category for the PubMed Clinical Queries.
Special Queries:
A directory of topic-specific PubMed queries.
Journal and Citation Subsets:
The table of journal and citation subset codes assigned to MEDLINE citations . See also Abridged Index Medicus (AIM or "Core Clinical") Journal Titles.
Journal Subject Terms:
Subject Terms are assigned by NLM at the journal level to describe each MEDLINE journal's overall scope.
Funding Support (Grant) Information in MEDLINE/PubMed:
An explanation and statistics of research funding support information on MEDLINE citations.
Computation of Similar Articles:
A white paper that explains the function of the Similar Articles feature.
What are the date ranges for past MeSH Indexing years?
Information about the date ranges for indexing with MeSH. Includes tips for searching.

TOOLS & UTILITIES

The Insider's Guide to Accessing NLM Data
The Insider's Guide is a series of educational resources to help users explore more powerful and flexible ways of accessing NLM data, with a focus on accessing PubMed data via the E-utilities API.
E-Utilities Quick Start:
The Entrez Programming Utilities (or E-Utilities) provide a method for accessing Entrez (including PubMed) data outside of the regular Web query interface.
LinkOut:
The service that links PubMed records to full text providers and other external resources related to the citation.
NLM Data Distribution:
Information on downloading bulk MEDLINE/PubMed and other NLM data.
PMCID/PMID/NIHMSID Converter:
Convert PubMed IDs to PubMedCentral IDs or NIH Manuscript System IDs. Convert PubMedCentral IDs to PubMed IDs.

MEDLINE® STATISTICS

MEDLINE PubMed Production Statistics:
Citations indexed, journal titles, number of searches, Web/Interactive, and Script/E-Utilities.
Key MEDLINE Indicators (Archived Version):
Citations indexed, number of searches, journal titles, citations keyboarded, OCRed and retrieved via XML; retractions, errata and comments.
Number of Titles Currently Indexed (Archived Version):
The number of journal titles currently indexed for MEDLINE in PubMed.
MEDLINE Selection Statistics:
Statistics on journal titles reviewed and selected by the Literature Selection Technical Review Committee (LSTRC) by date, country, and format.
Citations Added to MEDLINE by Fiscal Year:
Total of indexed citations by fiscal year.
Funding Support (Grant) Information in MEDLINE/PubMed:
An explanation and statistics of research funding support information on MEDLINE citations.
Statistical Reports on MEDLINE/PubMed Baseline Data:
Total citations containing each data element; total occurrences of each element; minimum/average/maximum occurrences of each element in a record; minimum/average/maximum length of a single element occurrence; average record size; and other statistical data describing the content and size of the elements. Various data from 2002-.
- Selected Statistics:
  - Citation Counts by Year of Publication:
    Total number, number published in the U.S., and percent published in the US for each year of publication.
  - Authors per Citation:
    Number of personal authors and collective authors per citation, and trends over time.
  - Number of Citations to English Language Articles; Number of Citations Containing Abstracts:
    By date ranges, the number and percent of citations to English language and non-English language articles, and number and percent with abstracts.

HELP & TRAINING RESOURCES

PubMed Online Training Resources:
PubMed tutorials, Quick Tours, classes and more. See also NLM's Learning Resources Database.
Classroom Training (National Network of the National Library of Medicine Training Office):
Free PubMed courses available for health sciences librarians and information specialists in the United States.
Frequently asked questions about MEDLINE, PubMed and PubMed Central (PMC):
NLM Support Center Knowledge Base on literature resources from NLM.
PubMed Help:
Searchable Help document for PubMed, available on the NCBI Bookshelf.

Last Reviewed: June 4, 2019