This study evaluated the effectiveness of a Weight Watchers program for patients with schizophrenia who had olanzapine-related weight gain and ascertained whether the severity of patients' psychiatric symptoms was correlated with the patients' success in losing weight. Seven men and four women who had been treated with olanzapine and who had gained at least 7 percent of their pretreatment body weight attended Weight Watchers meetings and were offered supervised exercise sessions. The patients' weight, body mass index, and psychiatric symptoms were assessed and were compared with those of a matched comparison group who did not attend the Weight Watchers program. Only the men experienced significant weight loss. No correlation was found between weight loss and exercise or change in psychiatric symptoms.