The OntoVIP ontology was developed in the context of the Virtual Imaging Platform project (VIP), a french project supported by ANR (ANR-09-COSI-03 grant) aiming at sharing medical image simulation resources. This ontology describes the content of the models used in medical image simulation. This ontology can be used to annotate such models in order to highlight the different entities that are present in the 3D scene to be imaged, i.e. anatomical structures, pathological structures, foreign bodies, contrast agents etc. The model allows also to associate to these entities information about their physical qualities, which are used in the medical image simulation process (to mimick physical phenomena involved in CT, MR, US and PET imaging). This ontology partly relies on the OntoNeuroLOG ontology (ONL-DP ONL-MR-DA), as well as PATO, RadLex, FMA and ChEBI.