Background Forensic psychiatric patients are at risk to cause damage to society in the future again, both materially and immaterially. Little is known about the pharmacotherapeutic or psychotherapeutic treatment of the specific psychopathology of forensic psychiatric patients. This is possibly due to scarcity of research in the field, which could be caused by the fact that forensic psychiatric patients are often unwilling to participate in scientific research. Aim To explore the reasons why patients are unwilling to participate in research. Method Sixty-five forensic psychiatric patients were asked about their opinion on participating in pharmacological, psychotherapy, MRI- and DNA research. Results The main reasons for not participating in pharmacological research were 'patient's belief that they will not benefit from participation in research' and 'physical integrity' (the fear of being physically harmed by participation in research). 'General resistance' (not willing to take part for no particular reason) was the main reason for not participating in psychotherapy-, MRI and DNA research. Conclusion In order to enhance willingness to take part in research, informing the patients in the right manner with the aim of taking distrust away, would be important. Also, it could be helpful to offer a reward for participation in scientific research, although this could lead to ethical complications.