The LUMC clinical ontology is a standard for efficient biomedical research in academic hospitals such as the LUMC. It is an ontology represented in OWL, a Semantic Web W3C recommended standard, to facilitate meaningful integration of different patient data within a hospital as well as to improve interoperability of clinical data, i.e. the “I” in the FAIR principles, for queries across external Linked Open Data and other clinical datasets from other hospitals on the Web.