Objective:To observe the effect of Jiakang formula on thymus,pituitary and spleen pathological changes of ex- perimental hyperthyroid rat.Methods:40 rats were used Euthyrox daily at 75 μg/100g ig and were randomly divided into hy- perthyroidism model group, control group, middle dose Jiakang formula group, high dose Jiakang formula group, each with 10 rats,and there were 10 rats as normal group.Three weeks latter the rats were killed for observation the effect of Jiakang for- mula on thymus,pituitary and spleen pathological changes of experi...