Abstract: The effects of Total Glycosides of Tripterygium Wilfordii (T_II), a traditional Chinese medicine, on heteratropic heart allograft and lymphocyte trensformation of spleen cell were investigated in rat. The results show that （1） T_II can prolong the mean survival time （MST） of rat heart allografts: （2） T_II can inhibit T lymphocyte multiplication, and this may be one major mechanisms of T_II actions. In addition, hepatotoxic, or nephrototoxic action and the influence on peripheral blood WBC count are not found in T_II treatment.