Objective: The aim of this study was performed to determine the effectiveness of acceptance and commitment therapy on psychological flexibility in obese women in Isfahan, Iran.

Materials and Methods: This was a quasi-experimental pre-test, post-test trial with follow-up. The study population was all of the obese women in Isfahan in 2014 (BMI≥30).the sample of study was selected by convenience sampling method. They were randomly assigned to two experimental and control groups (15 per group). The Acceptance and Action Questionnaire for Weight-Related Difficulties (Lillis & Hayes, 2008) was the study instrument. The intervention was 8 sessions of 90 minutes. Acceptance and commitment therapy was provided only to the experimental group. Data was analyzed by SPSS.

Results: Results of covariance analysis showed a significant increase in psychological flexibility at post-test and follow-up stage (P<0.05).

Conclusion: Our findings showed that acceptance and commitment therapy has been effective on psychological flexibilityof obese women.