ABSTRACT
This project evaluated the prevalence of obsessive-compulsive disorder in two disorders of schizophrenia and bipolar I. Using a cross sectional plan, 150 patients were selected from the psychiatric clinic of Tabriz Educational and Treatment Center through available sampling. They were diagnosed with either bipolar or schizophrenia on the basis of DSM-IV criteria. The diagnosis of obsessive-compulsive disorder was assessed via unstructured interview and Yale-Brown Obsessive-Compulsive Scale. 17 out of the 75 bipolar I patients [23%] and 27 out of the patients with schizophrenia [36%] had been afflicted with obsessive-compulsive disorder sometime during their life long. The prevalence of obsessive-compulsive disorder is observed at a considerable rate in patients with schizophrenia and bipolar disorders