Aims: Substance use disorder is a problem that causes serious familial conflicts. This study aimed to determine the effectiveness of acceptance and commitment therapy on increasing intimacy and marital adjustment of patients with substance use disorders.

Materials & Methods: This quasi-experimental study with pre and post-test design with one month control and follow-up was performed on all addict patients referring to Tehran, Iran Nouandisheh Drug Abuse Center during winter of 2018. 30 samples were selected by convenience sampling method and were randomly divided into two 15-people groups of experimental and control. Data were collected using Walker and Thompson Marital Intimacy Scale and Spanier Marital Adjustment Questionnaire. All participants completed pre-test, intimacy scale and adjustment questionnaire. The experimental group participated in Acceptance and Commitment Therapy sessions, and a week later, the post-test was held in both groups. A month later, follow-up test was performed in both groups. The data were analyzed using analysis of covariance and repeated measures ANOVA.

Findings: In the experimental group, the subjects' marital intimacy scores 34.53±12.20 and marital adjustment 33.73±11.95 after intervention were 60.40±16.59 and 56.46±13.21, respectively increased (p<0.05). This increase did not apply to the control group (p<0.05). Effect size also indicated that about 581% of marital intimacy and 0.414% of marital adjustment in the experimental group were affected by acceptance and commitment therapy. There was a significant difference between pre-test, post-test and follow-up of the experimental group in the intimacy index (F=54.035; p<0.01) and marital adjustment (F=26.988; p<0.01).

Conclusion: Acceptance and commitment therapy continuously increase intimacy and compatibility of couples with substance use disorders