The Middlesex Hospital Questionnaire (MHQ) was used as a screening test for psychiatric disorder in 169 new outpatients. The profile obtained on the six subscales of the MHQ was strikingly similar in this American sample compared to four previous British reports. The MHQ significantly differentiated between diagnostic groups, most particularly between neuroses and personality disorders. Moreover, 75 per cent of the patients could be correctly classified as either neurosis or personality disorder on the basis of their MHQ total and subscale scores. The MHQ appears to be particularly useful in identifying phobic disorders, and the phobia subscale consistently discriminated between anxiety-phobic states and other diagnostic groups.