PMC Open Archives (OAI) Service

The PubMed Central OAI service (PMC-OAI) provides access to metadata of all items in the PubMed Central (PMC) archive, as well as to the full text of a subset of these items.

PMC-OAI is an implementation of the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH), a standard for retrieving metadata from digital document repositories. Visit the Open Archives Initiative site for more information about the protocol and other activities of the OAI group.

PMC-OAI supports OAI-PMH version 2.0. It does not support earlier versions of the protocol.

Most of the items in this archive are copyright protected, with copyright held by the author(s) or the depositing journal. In general, the OAI service can not be used to retrieve the full text of articles in PMC. The only exceptions to this policy are for articles that are in the public domain and those that are made available under an Open Access provision (as defined in the Open Access Subset). See the PMC copyright notice for more information.

High-Volume Retrievals

If you are using a script that makes more than 100 requests of any kind, please run it outside of the PMC system's peak hours. Do not make more than one request every 3 seconds, even at off-peak times. Peak hours are Monday to Friday, 5:00 AM to 9:00 PM, U.S. Eastern time.

Access to Full Text

Some PMC journals allow harvesting of the full text of all items, others allow it for only some items, and many do not allow it at all. See the PMC Open Access Subset for specifics.

In addition, the parameter set=pmc-open identifies the complete collection of items in PMC for which the full text may be harvested.

Supported Data Formats

Records may be retrieved from the PMC archive in one of the following formats:

The NLM Journal Archiving and Interchange XML format, for metadata or full-text article records. A DTD, W3C Schema, and complete documentation for this format are available from http://dtd.nlm.nih.gov.

Use metadataPrefix=pmc_fm for metadata,
and metadataPrefix=pmc to get the full text of an item.
The Dublin Core format, for metadata only (metadataPrefix=oai_dc). Information about Dublin Core is available at http://dublincore.org

Automatic Segmentation of Large Result Sets

If a ListIdentifiers request results in more than 500 hits, PMC-OAI will return the first 500 with a <resumptionToken> that can be used to get the remaining items.

If a ListRecords request results is more than 25 hits for PMC full text, 50 hits for PMC metadata, or 50 hits for Dublin Core format metadata, PMC-OAI will return the first 25, or 50 records, respectively, with a <resumptionToken>.