The per capita expenditure for health care of patients with multiple physical symptoms but no apparent physical disease (somatization disorder) is up to nine times the average per capita amount. We conducted a randomized controlled trial to determine whether psychiatric consultation would reduce the medical costs of these patients, without effecting a substantial change in patient outcome. Thirty-eight patients were randomly assigned to treatment or control groups and studied prospectively for 18 months. Treatment consisted of a psychiatric consultation and suggestions on management given to primary physicians. After nine months, the control group was crossed over to receive treatment with the same intervention. After the psychiatric consultation, the quarterly health care charges in the treatment group declined by 53 percent (P less than 0.05). In contrast, the charges in the control group showed wide variations but no overall change. The quarterly charges in the control group were significantly higher than those in the treatment group (P less than 0.05). After the control group was crossed over to receive treatment, their quarterly charges declined by 49 percent (P less than 0.05). The reductions in expenditures in both groups were due largely to decreases in hospitalization. We conclude that psychiatric consultation in the care of patients with somatization disorder reduced subsequent health care expenditures without inducing changes in health status or patients' satisfaction with their health care.