Introduction: Obsessive-compulsive disorder, despite its relatively low prevalence of mental disorders among the most complex and interesting. that many factors can influence on it. The current study was Role of Styles of thinking styles and attributional styles and optimism and pessimism in the prediction of obsessive-compulsive disorder. Materials & methods: This was a correlation study and consisting of all patients with obsessive-compulsive disorder referring to psychiatric clinics, from Ardabil in 1391. Thee xact figures werenot accessible. Among this population, forty patients having OCD were selected. In order to collect data, OCD questionnaire, Maudsley practical, Sternberg thinking style questionnaire , Seligman attribution style questionnaire, were applied and the revised and life directional questionnaire. Findings: The collected data multiple regression analysis. The conclusions indicated that depicted that there is a significant correlation among thinking styles, instruments, and attributional styles, optimism and pessimism which predict obsessive-compulsive symptoms. The most predictive variables were optimism and pessimism, respectively. Discussion & Conclusion: Obsessive disorder it causes problems in family practice and risk for patients. These results demonstrate the prominent role of thinking styles, attribution styles, optimism and pessimismin forming and developing compulsive thought which ispragmatic