Background and Objective: Today in the third wave of psychotherapy, it is claimed that individuals with cognitive flexibility, awareness, and acceptance of thoughts can modify their feelings and behaviors. The purpose of this study was to determine the effectiveness of group therapy based on acceptance and commitment in the reduction of craving and the improvement of quality of life in addicts receiving methadone treatment.
Materials and Methods: In this quasi-experimental study, the statistical population includes all male addicts receiving methadone treatment in Zanjan in 2015-2016. A sample of 30 subjects was selected through convenience sampling and later they were randomly assigned to intervention and control groups. The intervention group participated in 8 sessions of 90-minutes group therapy based on acceptance and commitment.  Craving questionnaires of Franken et al. (2002) and quality of life (SF-36) were conducted in the form of pre-test, post-test and a quarterly follow-up period in both groups.
Results: Group therapy based on acceptance and commitment could effectively reduce craving and increase mental health (P <0.05). The effectiveness of this intervention in increasing physical health was not statistically significant (P> 0.05). The effects of group therapy based on acceptance and commitment on post-test craving and mental health in quality of life were significant in comparison to the control group and these effects remained stable over a quarterly follow-up period.
Conclusion: The present study showed that acceptance and commitment therapy is effective in decreasing craving and improving mental health.