When a congenital uterine anomaly has been diagnosed, surgical correction of the malformed uterus is usually carried out. However, minor disturbances of glucose metabolism are easily overlooked in the presence of major congenital uterine malformation. In this paper we studied the obstetrical histories of 76 patients with congenital uterine anomalies. In the group with repeated pregnancy failure we found significantly more disturbances in carbohydrate metabolism than in the group with uneventful pregnancies (P less than 0.001). Treatment of any disturbances of carbohydrate metabolism greatly improves the fetal outcome. This suggests that such treatment is essential in the management of patients with a bad obstetrical history and may even make surgical correction unnecessary.