Open healthCare Ontology (OpenCare) is an integrated metadata vocabulary expressed as an ontological data model, to facilitate the effective reasoning of patient-specific electronic health record (EHR) data. The OpenCare model identifies the concepts and semantic types in the EHR data with the aim of enabling the representation of clinical data in a way that is accessible and usable by researchers and healthcare facility users. The development of OpenCare and its components is formalized using the Ontology Web Language (OWL). This framework aims to enhance the accessibility and user-friendliness of EHR clinical data.