Background & objectives: Psychological problems of chronic patients, especially diabetes, that often are ignored, need special attention to proper treatment. The aim of this study was to investigate the effectiveness of acceptance and commitment therapy on psychological symptoms, coping styles and quality of life in patients with type-2 diabetes.

Methods: The research design was a semi-experimental one with pretest-posttest and control group format. The sample included all in patients with type II diabetes who referred to Taleghani Diabetes Hospital in Kermanshah city in 2014-15 (N=490), who were assessed based on DSM_IV_TR criteria, DASS-21, WHOQOL-26, and coping styles. Those who got highest scores were selected. The study subjects, were randomly divided into experimental and control groups (n1=n2=8). The experimental group was exposed to 8 sessions of two hours ACT. The data was analyzed using descriptive statistics and multivariate analysis of covariance (MANCOVA) by SPSS-16 software.

Results: The results showed significant difference between experimental and control groups total scores in depression, anxiety, stress, coping styles (Problem Solving, Emotional, Avoidance), (p<0.05). Also, quality of life, psychological, social and environmental health components had significant difference, (p<0.05), but no difference was observed in physical health (p>0.05).

Conclusion: The results emphasize the importance of this intervention in psychosomatic and chronic diseases and provide new horizons in clinical interventions.