The authors report on a controlled examination of the effects of mental health intervention on the use of medical services in a health maintenance organization. Thirty-six patients were randomly assigned, after initial evaluation, either to begin immediately short-term (15 weekly session) group therapy or for those same 15 weeks to remain on a waiting list. The results seemed to indicate that both patients treated immediately and patients who were wait-listed reduced their medical utilization. Wait-list patients, however, appeared to reduce health care use more than immediate-treatment patients. Further, examination of the patterns of health care use showed that wait-listed patients were more likely to have changed their patterns of utilization than immediate-treatment patients. These findings, which must be interpreted cautiously because of the small number of subjects, appear to support the results of other studies that indicate that those patients with the least mental health intervention appear to have the greatest reductions in medical utilization.