Fourteen obese children and adolescents were treated with a combined therapy of low calorie diet and exercise and their progress compared to that of 11 obese children treated with diet only. Children treated with combination therapy were encouraged to perform aerobic exercises daily, for a period of time which was calculated to consume approximately 250 kcal per exercise session. After 4 months of therapy, a significantly (P less than 0.05) larger decrease of % overweight was observed in the group of children treated with diet and exercise (-25 +/- 13.5%) than in those treated with diet only (-15.8 +/- 10.5%). Treatment compliance was better in the group treated with diet and exercise than in the group which followed a low calorie diet only. We think that unsupervised exercise therapy can be successfully combined with a low calorie diet in the treatment of childhood obesity.