If ontology is the solution, what is the problem?

In this paper we show the usefulness of an ontological approach for solving some problems arising in medicine. We point out the relevance of terminological ontologies for disambiguating polysemous terms, for re-organizing very large corpora and detecting possible inconsistencies and for managing a catalog of bio-medical equipments. We also put in evidence the fundamental role played by ontologies when integration and interoperability of heterogeneous knowledge sources is needed, in particular in the field of clinical guidelines and evidence-based medicine.