The authors assessed data from 1,148 outpatients in a 10-week medical symptom reduction program to determine the effectiveness of a behavioral medicine intervention among somatizing patients. The program included instruction in the relaxation response, cognitive restructuring, nutrition, and exercise. Before and after the intervention, the patients were evaluated on the Symptom Checklist-90 Revised (SCL-90R), the Medical Symptom Checklist, and the Stress Perception Scale. They were divided into high- and low-somatizing groups on the basis of the pretreatment SCL-90R somatization scale. At the end of the program, physical and psychological symptoms on the Medical Symptom Checklist and the SCL-90R were significantly reduced in both groups, with the reductions greater in the high-somatizing group. Improvements in stress perception were about the same in both groups, but the absence of an untreated control group precluded estimates of how much the improvements resulted from the behavioral medicine intervention and how much from natural healing over time.