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The OLDMEDLINE subset in PubMed® represents journal article citations from two print indexes: Cumulated Index Medicus (CIM) and the Current List of Medical Literature (CLML). Created by the National Library of Medicine® (NLM®), there are approximately 2,011,000 article citations from international biomedical journals that cover the fields of medicine, preclinical sciences and allied health sciences from 1946 through 1965. OLDMEDLINE records, which are included in the MEDLINE® database, can be searched via PubMed.

Important Note About Coverage

The OLDMEDLINE subset in PubMed contains citations from the 1960 through 1965 Cumulated Index Medicus (CIM) print indexes and the 1946 through 1959 Current List of Medical Literature (CLML) print indexes. The OLDMEDLINE subset does not include citations from the Quarterly Cumulative Index Medicus (QCIM) print indexes. A hand search of the QCIM print indexes is necessary to ensure comprehensive review of medical periodical literature of the world from 1946 through 1956.

Publications History

In 1879 the Library of the Surgeon-General’s Office began publication of a monthly index to medical periodical literature of the world under the title Index Medicus (IM).

In 1916, the American Medical Association began publication of the Quarterly Cumulative Index to Current Literature (QCICL) using titles listed in the Current Medical Literature Section of the Journal of the American Medical Association. This index did not attempt to be inclusive; final volume of 1926 covered the contents of only 326 periodicals.

The IM and the QCI were published concurrently until 1927 when they combined to form the QCIM. Although greatly expanded, the QCIM continued to follow a policy of selectivity. The QCIM was oriented toward the practicing physician—it concentrated on clinical subjects and was highly selective of research communications. The 1927 issue covered the contents of 1,165 periodicals.

In 1941, the National Library of Medicine began publication of the CLML, "a weekly list of contents of some of the more useful medical journals" received in the library. CLML and QCIM were concurrently published through 1956. The QCIM selectively covered 905 periodicals and indexed about 60,000 articles annually, the CLML covered about 110,000 articles. Duplication between the two periodicals occurred.

QCIM ceased publication with volume 60 in 1956. The medical literature of 1957-1959 was covered by the CLML. Beginning January 1960, both publications were superseded by CIM. See also: How can I identify older medical journal articles?


In 1964, NLM began using the computerized MEDLARS® (Medical Literature Analysis and Retrieval System) as a mechanism for producing Index Medicus®. In 1971, MEDLARS went online with the introduction of MEDLINE, an interactive searchable database of citations that grew to include the 1966 Index Medicus forward. The 1964 and 1965 issues of Index Medicus, while available in electronic form, were not included in MEDLINE because of format differences. In the mid-1990s, NLM was assisted in its effort to provide online access to these older citations by the Deutsches Institut für Medizinische Dokumentation und Information (DIMDI), the International MEDLARS Center in Germany. DIMDI had tapes of the original data from the 1964 and 1965 Cumulative Index Medicus, which they converted and then supplied to NLM to create OLDMEDLINE in 1996. The citations from the 1960 - 1963 CIM and the 1946 - 1959 Current List of Medical Literature (CLML) were converted from print copy into machine-readable form.


Date Added Citations Added From Print Index
December 1996 153,127
1965 CIM
1964 CIM
November 1998 233,654
1962 - 1963 CIM
1960 - 1961 CIM
July 2000 106,301
1959 CLML
1958 CLML
May 2002 103,427 1957 CLML
May 2003 105,757
1956 CLML
1955 CLML
1954 CLML
1953 CLML
February 2004 89,557
1952 CLML
1951 CLML
September 2004 55,850 53,533 citations from 1950 CLML
2,317 citations from 1951 - 1965*
December 2007 55,557 1949 CLML
February 2008 2,332 1949 CLML additional citations*
October 2008 70,046 1948 CLML
March 2010 63,839 1947 CLML 
November 2010 49,428 1946 CLML 
February 2014 11,845 Citations from 1950-1965*

*In order to load OLDMEDLINE data into PubMed, each citation must be linked to a parent serial record in LocatorPlus Catalog ®. Determining the proper link for some of these older citations takes research time which can result in the citations being made available later than the online debut date for the majority of a year's index. Research and user reports also uncover gap issues that NLM adds and citations that are duplicates that NLM deletes; these changes are not reflected in the counts given in the chart.

NLM expects to continue converting citations from its older print medical indexes to machine-readable form and will add these citations to PubMed as time and resources permit. OLDMEDLINE citations are tagged with the Citation Subset [SB] code OM and are searched as jsubsetom in PubMed.

Data Quality

OLDMEDLINE records have been created using standards that are different from the data entry standards for MEDLINE records. The format and data elements (fields) present in the OLDMEDLINE citations vary depending on the original source from which the citations were obtained. For details, see the individual MEDLINE/PubMed Data Element (Field) Descriptions.

OLDMEDLINE citations lack the individual and accumulated changes and improvements that have been made to data in other NLM files during annual file maintenance. Certain fields may contain outdated or erroneous data. Additionally, the data are not cosmetically consistent from year to year (e.g., the use of upper/lower case). The citations basically reflect the contents of the original print indexes that were produced under policy and procedures of the time. The exceptions to this are that NLM has identified and updated the Journal Title Abbreviation and added the appropriate ISSN. Each OLDMEDLINE citation is linked to a parent serial record in the NLM online catalog, LocatorPlus Catalog . In addition, beginning with 2005 Year-End Processing, OLDMEDLINE citations with Medical Subject Headings (MeSH®) (see MeSH Mapping Project) are included in the individual and accumulated changes and improvements that are made to the NLM data during annual maintenance, which notably, includes updates to reflect changes to the MeSH vocabulary.


Note the following aspects of OLDMEDLINE subset citations when searching:

Lack of Abstracts

When searching OLDMEDLINE citations, it is important to remember that the absence of abstracts affects subject retrieval.

Original Subject Headings

To differentiate between the original subject headings from the print indexes and current MeSH, all original subject headings have been placed in the Other Term [OT] field of OLDMEDLINE subset records in PubMed. Note the following characteristics of these subject headings:

  • Few subject headings (approximately 3 - 5 per citation). The 1964 and 1965 citations tend to have more subject headings (approximately 3 - 8 per citation). See the Sample Record (PubMed Display) .
  • "Check tag" headings (e.g., ANIMALS, CHILD, INFANT) were applied inconsistently and should not be used to search.
  • Original subject headings have not been updated and may not match current MeSH vocabulary.
  • Subheading practice varied:
    • No subheadings on 1963 - 1965 CIM citations and 1950 - 1951 CLML citations.
    • Various subheadings on 1960 - 1962 CIM citations, 1946 - 1949 CLML citations, and 1952 - 1959 CLML citations.
  • All original headings designated as major topic (the exceptions are explained under the MeSH Mapping Project section).

Because these original subject headings are not current MeSH, the subject headings in the Other Term [OT] field of OLDMEDLINE subset citations do not relate to current hierarchical MeSH Tree numbers, and the MeSH search capabilities (i.e., "explosions") that collect indented (more specific) terms are not functional for these data in the OT field.

Sample Record: PubMed display format for a 1964 MEDLINE citation that originated from OLDMEDLINE

PMID- 14226373
DCOM- 19961201
LR - 20181201
IS - 0022-1198 (Print)
IS - 0022-1198 (Linking)
VI - 9
IP - 4
DP - 1964 Oct
PG - 485-91
LA - eng
PT - Journal Article
TA - J Forensic Sci
JT - Journal of forensic sciences.
JID - 0375370
RN - 0 (Blood Glucose)
RN - IY9XDZ35W2 (Glucose)
MH - *Autopsy
MH - *Blood Glucose
MH - *Clinical Laboratory Techniques
MH - *Diabetes Mellitus
MH - *Forensic Medicine
MH - *Glucose
MH - *Human
MH - *Pathology
MH - *Vitreous Body
EDAT- 1964/10/01
MHDA- 1964/10/01 00:01
CRDT - 1964/10/01 00:00
PHST – 1964/10/01 00:00 [pubmed]
PHST- 1964/10/01 00:01 [medline]
PHST- 1964/10/01 00:00 [entrez]
PST - ppublish
SO - J Forensic Sci 1964 Oct;9(4):485-91.

MeSH Mapping Project

In 2005, NLM began an OLDMEDLINE OT subject heading-to-MeSH heading mapping project. This project mapped the original subject headings assigned to the citations when they appeared in the print indexes to the current MeSH vocabulary. As of December 2015, 100% of OLDMEDLINE citations have at least one current MeSH heading and will, therefore, be retrieved by PubMed searches that incorporate MeSH Headings. Many of the subheadings attached to the original subject headings are not mapped because they tend to be phrases derived from the article title and vary greatly. The original subject headings are retained in the OT field. This mapping project began as a manual effort that was automated over time and culminated with the use of the Medical Text Indexer (MTI) on every OLDMEDLINE-derived citation to enhance the MeSH.

Please note: The majority of current MeSH headings added to OLDMEDLINE subset records have been added as Major MeSH Headings because sixteen of the eighteen years of data have only headings under which the citations appeared in the print indexes. However, two years of data, the 1964 and 1965 CIM, contain additional MeSH headings that do not represent the major point of the article yet are also set to Major status because the original distinction between major and not major had been lost over the years during various conversion efforts and NLM did not have the resources to restore that distinction. Remember, as explained above, that OLDMEDLINE citations have MeSH headings such as the commonly used check tags for Animals, Age groups, etc. applied inconsistently and that subheading practices varied greatly over the years. An asterisk denotes major topic, i.e., MH - *Autopsy. Geographic headings and most check tags do not have an asterisk.

The date of introduction of a MeSH heading is not a factor for the mapping of OLDMEDLINE citations. For example, ROENTGEN RAYS is mapped to X-RAYS which wasn't added to MeSH until 1975. For searching, this means there is likely a PubMed retrieval gap on the heading X-RAYS for the approximate timeframe 1966 - 1974 which should be addressed by alternate search techniques such as text words or related MeSH.

During Year-End Processing, non-major MeSH headings may be added to citations. The MeSH headings added are associated with Supplementary Concept Records (SCRs). Each SCR has an associated Main Heading(s), which is its Heading Mapped-to (HM) in the MeSH Browser. For example, when the RN - A25P3CP5S7 (bromfenacoum) is added to an OLDMEDLINE citation, then the MH - 4-Hydroxycoumarins is added as well.

OLDMEDLINE Status vs. Subset

Citations that have not had all of their original subject headings mapped to current MeSH will have the status tag [PubMed - OLDMEDLINE]. However, as of late 2015, all citations from the OLDMEDLINE print index sources have one or more current MeSH Headings mapped to current MeSH and, therefore, carry the status tag [PubMed - indexed for MEDLINE]. See Sample Record (PubMed Display). A search for medline [sb] in PubMed will include these records. As resources permit, additional citations from older print indexes will be added. Citations with OLDMEDLINE [sb] status may be reintroduced until these additional citations' OT terms are mapped. At that point, those citations will convert to MEDLINE.

To search for all citations that originated from the OLDMEDLINE print index sources, regardless of their status, search jsubsetom in PubMed.


It is important to note that there are also tens of thousands of citations in PubMed with a publication date that pre-dates 1965 and the status of [PubMed] that are the result of either the NLM Back Issue Digitization Project or are back issue citation submissions that pre-date the start of MEDLINE indexing from publishers of MEDLINE journals for issues. These citations do not originate from the old print indexes and there are no Other Terms or MeSH Headings on these citations.

See these NLM Technical Bulletin articles for additional information:


OLDMEDLINE subset records are included in PubMed.

Further Information

For information about OLDMEDLINE data or other NLM services, contact:

Customer Service
National Library of Medicine
8600 Rockville Pike
Bethesda, MD 20894
Telephone: 1-888-FINDNLM (1-888-346-3656) or (301) 594-5983

1Crawford, Susan. "Introduction." Cumulated Index Medicus. Vol. 1 Part 1: January-December 1960. 1961. Reprint. New York: Johnson Reprint Corporation, First 1963. Second 1968. Print.

Last Reviewed: March 1, 2024