This study examined the effect of anxiety on symptom reduction through a behavioral medicine intervention in a Mind/Body Medicine Clinic. Participants were 1,312 outpatients attending a 10-week behavioral medicine intervention which included training in the relaxation response, cognitive restructuring, exercise and nutrition. All of the patients had physical symptoms and were referred to the clinic by their physician. The Medical Symptom Checklist (12 major symptoms), Symptom Checklist 90 Revised (SCL-90R), Stress Perception Scale and the Health-Promoting Lifestyle Profile were administered before and after the program. Of the sample, 1,012 patients completed the program, and 911 completed the posttreatment assessment. Self-reported frequency of medical symptoms, degree of discomfort and interference with daily activities were significantly reduced as a result of the program. Anxiety and other psychological distress as measured by the SCL-90R and stress perception scales also showed significant reductions. Furthermore, health-promoting lifestyle functioning significantly improved. High levels of pretreatment anxiety predicted a decrease in the total number of medical symptoms endorsed. Behavioral medicine interventions are effective in reducing medical symptoms coinciding with improvement in anxiety. High anxiety at program entry may predict better outcome. Copyright 2001 S. Karger AG, Basel