The most commonly used classifications in health and biomedicine are now accessible as ontologies.

Some of the most widely used international classifications are available as ontologies from the National Center for Biomedical Ontology (NCBO).

Of those, five have now entered the "registered" state in the SEMIC.EU Clearing Process. They are:

Bio Portal Metadata
International Classification of Diseases (ICD)
International Classification of Functioning, Disability and Health (ICF)
International Classification of Primary Care
Medical Subject Headings

The NCBO of the United States provides tools and biomedical ontologies mainly to support biomedical researchers in biomedical investigation and clinical practice.

See also: Related repositories

NCBO's BioPortal