Abstract Background: The comorbidity of substance use and mood disorders and anxiety has been proven in various studies, and has led to many clinical implications. Objectives: The aim of this study was to evaluate the effectiveness of acceptance and commitment therapy (ACT) on depression and anxiety in individuals with substance use disorder. Methods: This was a quasi-experimental study with a pretest and posttest design with a control group. The statistical population of this study consisted of all people with substance abuse in Urmia in 2019 with 220 subjects. The sample consisted of 50 individuals with substance use disorders who were selected by purposive sampling and randomly assigned to experimental and control groups. The experimental group was trained for 8 sessions, each lasting 90 minutes, based on Acceptance and Commitment Treatment Protocol of Hayes et al. (2004), and the control group did not receive any intervention. In this research, the results were obtained using the following scales: Beck Depression Inventory and Beck Anxiety Inventory. Pre-test and post-test were performed in both groups. The collected Data were analyzed by multivariate analysis of covariance (MANOVA) using SPSS23 software. Results: The results showed that after controlling the effects of pre-test, there was a significant difference between the mean post-test scores of the two groups in both variables of depression and anxiety (P <0.05). Conclusions: Acceptance and Commitment Therapy is an appropriate strategy to improve depression and anxiety in people with substance use disorders and can be used as an effective intervention.
