Aims: One of the effective therapies for the improvement of substance abusers is cognitive-behavioral group therapy. The aim of this study was to determine the effectiveness of cognitive-behavioral group therapy on changing irrational beliefs and increasing self-concept of substance abusers in Ahvaz.

Materials & Methods: This semi-experimental study with pre-test and post-test design with control group was conducted among addicted men to variety of drugs in Ahvaz in 2018. Thirty subjects were selected by random available sampling method and randomly divided into experimental and control groups. Jones`s irrational beliefs questionnaire and Beck self-concept test were used to collect data. The experimental group received cognitive-behavioral group therapy in 10 sessions (60 minutes in per session). Data were analyzed by SPSS 21 software using multivariate analysis of covariance (MANCOVA).

Findings: The mean scores of irrational beliefs in both experimental and control groups reduced in post-test comparing to pre-test, but the difference between experimental and control groups was significant in post-test (F= ??; p<0.01). The mean scores of self-concept in both experimental and control groups increased in post-test comparing to pre-test, but the difference between experimental and control groups was significant in post-test (F= ??; p<0.01).

Conclusion: The cognitive-behavioral group therapy is effectiveness on reducing irrational beliefs and increasing self-concept of substance abusers.