In a sample of 276 Japanese adult patient attenders at two primary care clinics affiliated with the Department of Hygiene and Preventive Medicine at the Okayama University Medical School major depression was diagnosed in 5.8% and minor depression in 7.2% of patients studied. Functional impairment was significantly more severe in patients with either major or minor depression than in those not affected. None of the 36 patients with major or minor depression had received a diagnosis of depression or had been given antidepressant therapy. Possible explanations for the marked underdiagnosis of depression and lack of specific antidepressant therapy in these patients include severe stigma associated with a diagnosis of mental disorders, focus of the mental health system on hospitalization with consequent trivialization of mental problems in ambulatory patients, and the extraordinarily high work load of primary care doctors.