The Mini-International Neuropsychiatric Interview (MINI) is a short, structured diagnostic interview used as a tool to diagnose 16 axis I (Diagnostic and Statistical Manual) DSM-IV disorders and one personality disorder. Its original version was developed by Sheehan and Lecrubier. We translated the MINI into Japanese, and investigated the reliability and validity of the Japanese version of MINI. Eighty-two subjects participated in the validation of the MINI versus the Structured Clinical Interview for DSM-III-R (SCID-P). One hundred and sixty-nine subjects participated in the validation of the MINI versus an expert's professional opinion. Seventy-seven subjects were interviewed by two investigators and subsequently readministered by a third interviewer blind to the results of initial evaluation 1-2 days later. In general, kappa values indicated good or excellent agreement between MINI and SCID-P diagnoses. Kappa values indicated poor agreement between MINI and expert's diagnoses for most diagnoses. Interrater and test-retest reliabilities were good or excellent. The mean durations of the interview were 18.8 min for MINI and 45.4 min for corresponding sections of SCID-P. Overall, the results suggest that the MINI Japanese version succeeds in reliably and validly eliciting symptom criteria used in making DSM-III-R diagnoses, and can be performed in less than half the time required for the SCID-P.