The aim of this study was to compare the effectiveness of metacognitive therapy, fluvoxamine and the combination of metacagnitive therapy with fluvoxamine in treatment of patients with OCD. Inclusion criteria were as follows: (1) diagnosis of OCD according to DSM-IV-TR, (2) age between 18 to 50. Patients were excluded if they had a personality disorder, substance abuse problem and other comorbid axis I disorders. Twenty-one outpatients meeting criteria for OCD without any other axis I and II disorder were randomly assigned to one of three treatment conditions: MCT, fluvoxamine and combined group for 10 weeks of treatment. The demographic Questionnaire, Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), Beck Depression Inventory-II-Second Edition (BDI-II), Beck Anxiety Inventory (BAI), Depression Anxiety Stress Scale-21 (DASS-21), Subjective Units of Distress (SUDs), Global Assessment of Functioning (GAF), Metacognitions Questionnaire-Short Form (MCQ-30), Thought Control Questionnaire (TCQ), and Stop Signals Questionnaire (SSQ) were administered blindly at pre-treatment and post-treatment. Y-BOCS, BDI-II, BAI, DASS-21, SUDs and GAF also were administered after session 2, 4, 6 and 8. Nineteen patients completed this study and two patients dropped out from the study. ANCOVA, repeated measure ANOVA, pre- to post improvement percentage, Kruskal Wallis and mann Withney U-test are used to analyze data.