This study assessed the efficacy of a weight control program for patients taking atypical antipsychotics. Thirty-one patients with schizophrenia or schizoaffective disorder participated in a 12-week weight control program that incorporated nutrition, exercise, and behavioral interventions. Changes in patients' weight and in body mass index (BMI) were recorded and compared with those of 15 patients in a control group. The intervention group had a mean weight loss of 2.7 kg (six pounds) and a mean reduction of.98 BMI points, compared with a mean weight gain of 2.9 kg (6.4 pounds) and a mean gain of 1.2 BMI points in the control group. These data suggest that the intervention was effective in this group of patients. Professionals treating persons who are taking atypical antipsychotics should encourage them to engage in weight control activities.