The aim of the present study was to provide basic descriptive data regarding utilization of 12-month mental health services in the Japanese community population. Face-to-face household surveys were carried out in four areas (two urban cities and two rural municipalities), and a total of 1663 persons participated (overall response rate: 56.4%). For data collection, the structured psychiatric interview, World Mental Health version of the World Health Organization Composite International Diagnostic Interview (WMH-CIDI) was used, allowing DSM-IV diagnoses, severity, and service utilization. It was found that 7.3% of total respondents had received any service, either professional or non-professional, in the past 12 months, including 20.0% of those with 12-month DSM-IV disorders and 6.2% of those without. Thirty-three percent of those with any mood disorder used any service, and 26.8% of those used some type of health care. The probability of people with 13-15 years of education receiving mental health treatment was fourfold higher than those with >or=16 years of education. Gender, age, or income were not found to contribute to utilization of mental health services. The results confirm that the majority of people with a recent psychiatric disorder have not used mental health care or other support systems. The mental health care system in Japan has improved over the past decade, but not enough for people suffering from mental disturbances.