OBJECTIVE To evaluate the usefulness of dexfenfluramine as an adjunct to a group treatment program for obese infertile women. METHODS Twenty-one obese infertile women were referred by the Reproductive Medicine Unit. They attended a 24-week group program which included exercise and educational sessions. Dexfenfluramine and placebo were given, each for 12 weeks, in a double-blind crossover design. RESULTS Dexfenfluramine treatment was not associated with greater loss of weight. The mean weight loss during dexfenfluramine treatment was 3.21 kg (SD 3.09) and during placebo was 3.31 kg (SD 3.15). Self-esteem, anxiety, and depression ratings all improved significantly over the 24 weeks. CONCLUSIONS The group treatment program appeared to be equally effective with or without dexfenfluramine. Previous studies have found dexfenfluramine to be effective in combination with individual treatment, but it has not previously been evaluated as an adjunct to group treatment. It is unclear whether dexfenfluramine may be less effective in combination with group treatment programs, or whether its usefulness is restricted in this particular population of obese patients. No differences were found associated with the order in which active and placebo treatments were given. Patients showed improvement in self-esteem and reduction in depression and anxiety, but dexfenfluramine treatment was not associated with any difference in these measures, compared to placebo.