Case Based Reasoning (CBR) is a problem-solving paradigm that uses knowledge of relevant past experiences (cases) to interpret or solve new problems. An evolvement to this paradigm is ontology-based CBR, an approach that combines, in the form of formal ontologies, case speci¯c knowledge with domain one in order to improve the e®ectiveness of the CBR process. This e®ectiveness is further improved if ontology- based CBR systems were able to utilize knowledge that is vague or im- precise; to that end, we present in this paper a novel CBR approach that manages and utilizes imprecise knowledge through the integration of Fuzzy Algebra in the ontology-based CBR paradigm. The approach has been applied in real life and constitutes the core of a portal that provides the public with intelligent access to knowledge assets.