Paper deals with the principles of model-driven UML Class model enhancement using business rules (BR) as a source of domain knowledge. Business rules are stored in BR repository which is defined by the business rules meta-model. Templates for business rules formalization are presented. Co-relations between BR meta-model and extended UML Class meta-model are also presented and discussed in this paper. Basic steps of the algorithm for the extended UML Class model enhancement are presented and illustrated with example.