A series of 215 patients treated surgically for Graves' disease between 1981 and 1988 were studied and compared with an earlier series of 105 patients operated upon in the same establishment between 1966 and 1980. More than 85 percent of the patients in the two series had long term follow-up evaluation. Surgical complications were rare in both series, with an overall morbidity rate of 2.7 percent, the rate of permanent recurrent laryngeal paralysis decreasing from 1 to zero percent and that of permanent hypoparathyroidism increasing from 1.0 to 1.9 percent. The incidence of residual or recurrent hyperthyroidism decreased markedly from 11.0 to 3.7 percent. This improvement can no doubt be attributed to bilateral subtotal lobectomy having been abandoned in favor of total lobectomy on one side and subtotal on the other. In contrast, this approach increases the incidence of hypothyroidism, with the rate rising from 13.0 to 48.7 percent. Long term monitoring is always necessary because results change during the course of time.