Purpose: To study the effects of Tianma Injection on the mouse's splenic lymphocyte proliferation in vivo and vitro. Methods: The proliferation of the ConA_stimulated splenic lymphocyte was measured with incorporation of 3H_methylthymidine( 3H_TdR) in mice. Results: Intra_abdominal injection of Tianma Injection ( 2.5 mg/kg,5mg/kg,10mg/kg and 20mg/kg) improved the splenic lymphocyte transformation of the ConA_stimulated mice. However, the studies showed the inhibition of the splenic lymphocyte transformation by 40mg/kg of Tianma Injection. In vitro, lower doses (0.05～100μg/ml ) of Tianam Injection helped an increased rate of 3H_TdR_uptakes whereas responsiveness of splenic lymphocytes to higher doses(200～400μg/ml) was not modified. Contrary to the splenocyte responses, activation by Tianma Injection (800μg/ml) was characterized by a decreases proliferation, when compared to the background count of unstimulated cells. Conclusions: The findings prove that lower doses of Tianma Injection can enhance certain parametere of splenic lymphocyte function in vivo and in vitro while higher doses suppress it.