The NCI Thesaurus and NCI Metathesaurus provide standard vocabularies for biomedical research. The content of the NCI Thesaurus is available for download in tab-delimited flat file format and Web Ontology Language (OWL) format.
Please follow the links below to the pages specific for each set of downloadable files. Links to licenses or terms of use specific for each product can be found in the download pages for those products.
NCI Thesaurus (NCIt) is NCI's reference terminology and core biomedical ontology, covering some 100,000 key biomedical concepts with a rich set of terms, codes, definitions, and relationships, including some 40,000 concepts used in FDA, CDISC, NCPDP, NIH and other coding standards.
NCI Metathesaurus (NCIm) provides a broad, concept-based mapping of terms from over 70 biomedical terminologies, whose 4,000,000 terms are mapped to 2,000,000 concepts representing their shared meanings.