The UMLS Semantic Network consists of (1) a set of broad subject categories, or Semantic Types, that provide a consistent categorization of all concepts represented in the UMLS Metathesaurus, and (2) a set of useful and important relationships, or Semantic Relations, that exist between Semantic Types. The Semantic Network is one of three UMLS Knowledge Sources developed as part of the Unified Medical Language System project.

Download the Semantic Network Files

Semantic Groups

The UMLS Semantic Network reduces the complexity of the Metathesaurus by grouping concepts according to the Semantic Types that have been assigned to them. For certain purposes, however, an even smaller and coarser-grained set of semantic type groupings may be desirable. The following principles were used to design the groupings: semantic validity, parsimony, completeness, exclusivity, naturalness, and utility. The Semantic Groups provide a partition of the UMLS Metathesaurus for 99.5% of the concepts.

The UMLS semantic groups are made available through a file called SemGroups.txt. There is one line in this file for each semantic type. The identifier and the name of the semantic group are repeated for each semantic type included in the group, before the identifier (TUI) and the name (STY) of the semantic type.

The Semantic Groups file is not distributed with the UMLS Full Release, but you can download it here:

Download the Semantic Group File