Abstract The purpose of this study is to describe customer-related knowledge utilisation in the collaborative relationships of professional service organisations. Within this specific context, knowledge transfer capabilities are emphasised as an important prerequisite in the utilisation process. Effective organisation-level knowledge utilisation is crucial in collaborative relationships of professional service organisations. In order to formulate a coherent service offering across different areas of expertise, for instance, it is beneficial to transfer customer knowledge between professionals, business units and functions. Knowledge utilisation across different expertise areas may also be an important prerequisite for an organisation's innovativeness and proactiveness in customer cooperation. Customer-related knowledge utilisation and related knowledge transfer processes are in this study approached from a relationship management perspective, and literature from organisation research, resource-based view and knowledge management is used as a theoretical basis. Empirically this study is based on a descriptive case study of two professional service firms in the field of business-to-business education and consultancy services. In the first case, an in-depth analysis of an organisation developing a collaborative relationship in the outsourcing situation is described. In the second case, additional views are given on organisational practices potentially facilitating customer-related knowledge transfer. Empirical results show that internal fragmentation in the professional service organisation seems to be, to a large extent, inherent in this type of organisation, and may cause many problems in customer-related knowledge transfer and thus in effective utilisation of that knowledge. These knowledge transfer inhibitors rise from an organisation's characteristics; its dominant logic, culture, structure and systems. These organisational characteristics are bound to the characteristics of knowledge itself: its tacitness, non-observability and complexity, and can have an inhibiting influence on knowledge transfer. However, in spite of the inherent forces causing internal fragmentation and inhibiting knowledge transfer, moderating practices of a well-planned relationship coordination system, customer knowledge and expertise codification, and cooperative working practices among the experts seem to help to maintain customer knowledge transfer and utilisation, and thus also continuity and value creation in the long-term relationships. This value creation can be seen to be based on accessing and integrating a wide variety of knowledge resources in order to create innovative, flexible and multifaceted service offerings. Value creation can also be based on organisational ability for generative learning in order to change prevailing organisational assumptions and to develop the operations model needed in collaborative relationship.