Abstract. Knowledge tailoring is a powerful tool to customize a system according to the particular view and interests of the user, in such a way that usability of the system becomes significantly improved. In this paper, the tailoring of an actor profile ontology is discussed in the context of a HomeCare integrated system that is being designed and implemented in the EU K4Care project. The paper analyzes different ways of implementing the automatic tailoring of an ontology. A tool called ATAPO, which has been designed and implemented to assist the user in this automatic tailoring is presented.