History and Objectives: Due to high prevalence of depression among MI patients, and due to their complications and because of lack of information regarding depression state in CCU environment, the present study was carried out in CCU department of Shahid Beheshti Hospital to assess the prevalence of depression among AMI patients in the winter of 1997.Materials and Methods: A descriptive study was carried out on patients with MI who admitted in CCU. 30 patients were selected in each month and their history of cardiac complications, past treatment were recorded from their patient's file. Patients lacking any moode disorders and those not on psychiatric treatment were selected for the study. Beck test was reformed on all patients. Its grade is from 0 to 3 and has 15 psychiatric topics and 16 physical topics; Beck's depression scale is as follow: 0-14; depression is in normal range of community, 15-30; mild depression, 31-47; moderate depression, 48-63 severe depression. Date were analyzed with EPI5 program.Results: 100patients (23 women and 77men) were studied. Patients with mild and moderate depression were among workers, and those with mild depression had some schooling or high school diploma. Moderate depression was lower among university graduates. Depression was more prevalent among patients with small family size. the prevalence of depression was 2-3 time higher among female patients. There is an increase in the incidence of depression in patients with MI and admission to CCU, however, there is no relationship between degree of depression and age, sex, education and job of the patients. Is there any increase in the incidence of depression among patients referred to CCU with MI? A Ion term study with greater number patients is required to address such a question. Conclusions: The present study addresses the female patients admitted to CCU departments and patients with small family size. The importance of CCU ward environment on the prevalence of depression is addressed.