In the last decade of the 20th century knowledge has gained importance in the economy. This lead to the emergence of knowledge-based activities: knowledge-intensive organizations, and particularly knowledge-intensive services. These organizations function as external knowledge sources for other organizations. Their performance depends largely on professional knowledge. Since their performance has an impact on the success of their clients, it is important to look at those factors which influence the knowledge transfer between service provider and client organization. Based on theory and empirical research, the paper addresses the specific aspects of knowledge transfer from knowledge-intensive business service organizations to client organizations.