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Unified Medical Language System® (UMLS®)

2015AA UMLS® Release Notes and Bugs

What's New


The 2015AA Metathesaurus contains more than 3.1 million concepts and 12 million unique concept names from over 170 source vocabularies.

One new RxNorm subsource added: 

  • Metathesaurus CMS Formulary Reference File (MTHCMSFRF)

32 English sources and 19 translation sources were updated.  These include MeSH®, MedDRA, RxNorm, and SNOMED CT® (English and Spanish).  A complete list is available in the Updated Sources section of the Release Documentation.  For more detailed information on changes in this version of the Metathesaurus, see the Updated Sources (Expanded) section.  Additional release statistics may be found in the Statistics section.

Semantic Types

  • As of 2015AA, 6 previously deprecated semantic types have been removed.  Any CUIs that were categorized with the deprecated semantic types are re-categorized with the parent of the deprecated semantic type.  The following table lists the semantic types that were removed along with their replacements.
Deleted Semantic TypeReplacement Semantic Type
Neuroreactive Substance or Biogenic Amine Biologically Active Substance
Organophosphorus Compound Organic Chemical
Carbohydrate Organic Chemical
Lipid Organic Chemical
Steroid Organic Chemical
Eicosanoid Organic Chemical



  • A full Metathesaurus subset now requires 24.1 GB of disk space.
  • The active release requires 23.2 GB of disk space.
  • MetamorphoSys now allows an additional connection option, TNS service name, when browsing RRF data in an Oracle database.

SPECIALIST Lexicon and Lexical Tools

  • The SPECIALIST Lexicon has been updated (2015 Release).
  • The Lexical Tools have been updated (2015 Release) and integrate data from the SPECIALIST Lexicon, 2015 Release. The Lexical Tools include the Full and Lite versions of lvg.2015.
  • The Metathesaurus index files were processed using the updated lvg files.

UMLS Learning Resources
2015AA Source Release Documentation Web pages will be published following the release.

Users who are new to the UMLS are encouraged to review the New Users' homepage. This page includes the new UMLS Quick Start Guide, online demonstrations, step-by-step guides, and a link to UMLS training materials.


There are no known problems for the 2015AA release. Please send any issues or concerns to NLM Customer Service.

UMLS Problems (Bugs) for Previous Versions

Release information for the RRF Browser