Propranolol has been utilized safely and successfully in the preparation for thyroidectomy in four pregnant patients with thyrotoxicosis. No ill effects were noted in mothers or infants. No change in fetal heart function was noted while two mothers were receiving propranolol. The major advantage of propranolol over the thiourea drugs is the rapidity with which the patient can be prepared for operation. Preparation with beta blockage can be accomplished in five to ten days. This limited experience suggests that propranolol is probably the drug of choice for preparation of the gravid thyrotoxic patient for whom thyroidectomy is planned.