This paper introduces a visual, UML-based notation for OWL ontologies. We provide a standard MOF2 compliant metamodel which
captures the language primitives offered by OWL DL. Similarly, we invent a UML profile, which allows to visually model OWL
ontologies in a notation that is close to the UML notation. This allows to develop ontologies using UML tools. Throughout
the paper, the significant differences to some earlier proposals for a visual, UML-based notation for ontologies are discussed.