The author reviewed and studied the peak values of 261 cases of Graves' diseases treated with 131Ⅰ before and after,and also sdudied the changing regulations of the peak values,and then pointed out that, no matter how the forword treating effects were,the peak va1ue decreased remarkably(P<0.001). Therefore, the ca1culation of the peak va1ue change is significant for antici pation after the patient being treated with 131Ⅰ one year later. The unchanged peak va1ue is <0. 1 the long-period hypothyroidism>0. 5, ...