A case is reported of a Senegalese patient admitted for hydatiform mole. The serum human chorionic gonadotrophin concentration (hCG) was 900,000 UI.l-1. The patient was recognized to be clinically hyperthyroid with raised T4 and T3 values, but a very low TSH concentration. After two days of beta adrenergic blockade and carbimazole, a suction curettage was performed under general anaesthesia. Propranolol was again administered 6 hours after the surgery. Thyroid function returned to normal level two weeks after removal of the mole, suggesting that hCG was responsible for the thyrotoxicosis. Serum hCG concentrations closely paralleled those of free thyroxine, but the correlation was difficult to assess because of carbimazole. Clinical thyrotoxicosis is rare in molar pregnancy. The diagnosis being made in semi-urgent conditions, this raises the question of how to obtain rapid stabilization of the disease before surgery.