The charts of 65 patients who completed mental health care referrals were compared with those of 65 patients who failed to complete such referrals. In the year before referral, the noncompliant patients made 37% more medical visits than the compliant patients. As compared with the compliant patients, a significantly greater proportion of the noncompliant patients' medical visits were for difficult-to-explain somatic symptoms. Mental health referrals from some physicians were much more successful than referrals from other physicians. By attending to their patients' pattern of health care utilization, primary care physicians may be able to identify patients at high risk for noncompliance with mental health referrals.