In the past few years, several studies have emphasized the use of ontologies as an alternative to information organization. The notion of ontology has become popular in fields such as intelligent information integration, information retrieval on the Internet, and knowledge management. Different groups use different approaches to develop and verify de effectiveness of ontologies [1] [2] [3]. This diversity can be a factor that makes it difficult the formularization of formal methodologies of evaluation. This paper seeks to provide a way to identify the effectiveness of the knowledge representation based on ontology that was developed trough Knowledge Based System tools. The reason for that is because all processing and storage of gathered information and knowledge base organization is done using this structure. Our evaluation is based on case studies in the Ontoweb system [4], involving real world ontology for money laundry domain. Our results indicate that modification of ontology structure can effectively reveal faults, as long as they adversely affect the program state.