Ninty-nine initial but untreated patients with hyperthyroidism were divided at random into three groups :propranolol, methimazole, and combined groups. Determination of serum T4, T3, rT3 and TSH levels together with STI and ICG were performed before and during treatment among these groups. The results showed that in the combined group, the fall of mean T3 levels to normal was the earliest and fastest, there was a better normalization of cardiac parameters, and the clinical manifestations could be brought under control rapidly. The combined therapy of propranolol with methimazole was especially advantageous to cases of mild and moderate hyperthyroidism.