Shahroud University of Medical siences International Journal of Health Studies 2423-6594 2022 05 08 Comparison of the Effectiveness of Metacognitive Therapy and Cognitive-Behavior Therapy on Intrusive Thoughts of Obsessive-Compulsive Disorder 10.22100/ijhs.v9i1.951 eng Sahar Sharifi Shahrivar Department of Psychology, Faculty of Psychology, Qods Branch, Islamic Azad University, Qods, Iran. Seyed Zabihallah Mosavian Department of Child and Adolescent Psychology, Payame Noor University (PNU), Bushehr, Iran. Seyyedeh Nasrin Mousavinia M.Sc. in clinical psychology, Department of Psychology, Faculty of Psychology, Neyshabur Branch, Islamic Azad University, Neyshabur, Iran. Neda Jamali Aghdavahlo M.Sc. in clinical psychology, faculity of psychology, Garmsar University,Garmsar,lran. Sara Masoumi M.Sc. Department of Educational Sciences 2, Faculty of Humanities, Abhar Branch, Islamic Azad University, Abhar, Iran.. Javad Seyed Jafari Ph.D. candidate in Psychology, Allameh Tabataba'i University, Tehran, Iran. 2022 01 27 2022 05 08 Background: According to WHO statistics, Obsessive-Compulsive Disorder (OCD) is the tenth most disabling condition. Thus, this study aimed to compare the efficacy of metacognitive therapy (MCT) against Cognitive-Behavior Therapy(CBT)  on intrusive thoughts in obsessive-compulsive disorder. Methods: In this study, a quasi-experimental design was used with pre-tests, post-test, and a control group. The study population was all patients who attended psychological clinics in Tehran, Iran, between August to September 2019. Using a purposeful sampling method, 24 OCD patients were selected from the study population, eight in every two experimental groups and eight in the control group. The experimental groups received 8, 120-minute sessions of therapy once a week. The study instruments were a questionnaire on demographic features and the Thought-Action fusion scale (TAFS). To analyze the data, inferential statistics (Multivariate Analysis of covariance (MANCOVA) by SPSS24. Results: The results revealed that MCT and CBT treatments had a significant effect on variables (Pvalue<0.05). As observed, there is a significant difference in all subscales between the two groups of experiment and control in pre-test and post-test, after removing the pre-test effect (Pvalue<0.05). Moreover, findings showed that both approaches significantly differ from the control group when comparing variables between the two treatments. However, MCT treatment had the greatest effect. Results: The results revealed that MCT and CBT treatments had a significant effect on variables (Pvalue<0.05). As observed, there is a significant difference in all subscales between the two groups of experiment and control in pre-test and post-test, after removing the pre-test effect (Pvalue<0.05). Moreover, findings showed that both approaches significantly differ from the control group when comparing variables between the two treatments. However, MCT treatment had the greatest effect. Conclusions: Both MCT and CBT were found to be effective in reducing intrusive thoughts, though MCT had a greater reduction than CBT. Keywords: Metacognitive therapy, Cognitive-behavior therapy, Intrusive thoughts obsessive-compulsive disorder