Service user involvement has become a common feature of education programmes for mental health students. However, little is known about the effects of this type of education on the interpersonal skills of students taking part. This paper reports findings from a systematic review that formed part of a wider investigation into service user involvement in teaching interpersonal skills. The review aimed to locate and assess the quality of the published evidence relating to the effects of service user involvement on mental health students interpersonal skills and to synthesize results, using a definition of interpersonal skill that includes attitudes, empathy and skills as its key components. Results from this study indicate that the quality of evidence in this area is poor. However, sufficient synthesis of the evidence base was possible to allow conclusions and recommendations for both research and practice. Conclusions were that the involvement of service users in this area is both acceptable and valuable for students and had specific impacts on attitudes, empathy and skills. Some difficulties and reservations about the style of involvement are discussed. Recommendations for the conduct of future research are also made.