In April 2007, the United States became one of nine charter members of the International Health Terminology Standards Development Organisation (IHTSDO), which owns Systemized Nomenclature of Medicine Clinical Terms (SNOMED CT). Because of this, licensees of the UMLS Metathesaurus have access to SNOMED CT (both English and Spanish versions) as part of the UMLS Metathesaurus and in its native file formats.

All UMLS Metathesaurus users are required to accept the SNOMED CT Affiliate Licence Agreement, even those who will not download the SNOMED CT native files or use SNOMED CT.

More information on SNOMED CT