To examine the frequency of psychiatric patients who visit outpatient clinic of non-psychiatrists in Japan, a mailed questionnaire survey was conducted of 200 non-psychiatrists randomly selected from the 703 registered members of the Kawasaki-city Medical Association, Kanagawa prefecture. Responses from 124 or 62% were received and data for 112 male respondents were analyzed. 1) The median number of psychiatric patients treated per month by respondents was 4, and the median proportion of the total outpatients that were psychiatric patients was 0.7%. 2) Sixty-one internists saw significantly greater numbers and proportions of psychiatric patients than the other 51 doctors. 3) The internists saw a higher proportion of mild anxiety, depression, alcohol-drug dependency and psychosomatic problems among all psychiatric patients than did other doctors. 4) For the internists a significant inverse correlation was observed between the total number of outpatients and the proportion of psychiatric patients. This was the result of a group of physicians who saw a relatively small number of outpatients but had a higher proportion of psychiatric patients among outpatients.