A randomized clinical trial was conducted in a group practice for the primary care of adult patients to address the effect of feedback to providers of information from a psychiatric screening questionnaire, the General Health Questionnaire (GHQ). The practice is staffed by faculty, residents, and health care extenders of The Johns Hopkins University School of Medicine's Division of Internal Medicine. The patient population was drawn mainly from the inner city community in Baltimore that surrounds the hospital, where the practice is physically based. The GHQ was administered at the time of a regular visit to the practice and results made available to the clinicians for randomly allocated subsamples of their patients. The study results showed that feedback of GHQ information led to only marginal effects on overall detection of mental health problems among the patients in general. However, marked increases in detection occurred among the elderly, blacks, and men, subgroups that ordinarily have relatively low rates of detection of mental morbidity by primary care practitioners. Feedback of GHQ information did not affect management.