In global economy, turbulent organization environment strongly influences organization's operation. Organizations must constantly adapt to changing circumstances and search for new possibilities of gaining competitive advantage. To face this challenge, small organizations base their operation on collaboration within Virtual Organizations (VOs). VO operation is based on collaborative processes. Due to dynamism and required flexibility of collaborative processes, existing business information systems are insufficient to efficiently support them. In this paper a novel method for supporting collaborative processes based on process mining techniques is proposed. The method allows activity patterns in various instances of collaborative processes to be identified and used for recommendation of activities. This provides an opportunity for better computer support of collaborative processes leading to more efficient and effective realization of business goals.