Background: The purpose of the study was to examine the effects of anger regulation cognitive behavior therapy on sexual cognitive distortions and rape proclivity on sexual offenders. Methods: The participants were sexual offenders who are currently imprisoned. The 37 participants were randomly assigned to either treatment group (n=18) or control group (n=19). The treatment group was administered 5 sessions (120-minute each). The program included how to recognize anger and practiced effective strategies to deal with it. All participants completed questionnaires at baseline and post-treatment. Results: No significant pre-post differences in anger, sexual cognitive distortions and rape proclivity were found between treatment group and control group. Conclusions: The findings suggest that anger regulation program is not enough to make significant differences in anger, sexual cognitive distortions and rape proclivity. However this study shows the potential possibilities of combination of anger regulation treatment and current CBT programs that would make current correcting programs for sex offenders more effective. Limitations and suggestions for further studies were proposed at the end.