Objectives: The purpose of this study was to investigate the effectiveness of cognitive-behavioral group therapy on improving coping skills and relapse prevention in addicts. Method: In a semi-experimental study, 30 in-dividuals who had been successfully detoxified at the Self Introducing Health Center in the city of Shiraz, Iran, were divided into an experimental (15 subjects) and a control (15 subjects) group. The experimental group underwent twelve 90 minutes sessions of cognitive-behavioral group therapy and the control group did not receive any particular treatment. All participants completed the Carver Coping Inventory at the beginning of the study and two months following the completion of treatment and underwent urine tests for morphine. Data were analyzed using descriptive statistics, c² and multiple analysis of variance. Results: c² test results showed significant difference in relapse rates of two groups (p<0.01). MANOVA showed a significant difference between the two groups regarding benefiting from problem oriented coping strategies and the interactive effect of problem oriented coping strategy in the post test stage (p<0.001). Conclusion: Cognitive-behavioral group therapy is effective in the improvement of coping skills and relapse prevention in addicts.