Although there are vast amounts of information accessible through Web technology, retrieving specifically related information through the Internet can still be difficult. In order to cope with this problem, the World Wide Web Consortium has developed an extension of the current Web called The Semantic Web. The Semantic Web is a standardized mechanism for obtaining meaningful definitions and a fundamental philosophic logic that relates entitites by means of integral relations (the basis for granularity) using conceptual ontology. In this article, the authors describe the essential features of OWL, an Ontology Web Language, and the Semantic Web, and outline their respective representations in Protégé. The authors then utilize OWL to formulate an ontology of blood pressure by extending Kumar and Smith’s original blood pressure case study to a domain composed of medical entities. We have a software package that comes with this paper to demonstrate the Ontology for Blood Pressure to a domain composed of medical entities.