Several experimental findings suggested that the regular swimming training induce immune response, but there have been few papers which compare swimming training with immune response in mice spenocytes. This study was designed to examine the effects of regular swimming training on Index, the number of lymphocytes, and proliferative activity by spenocytes in BALB/c mice. The trained mice underwent a 10-wk endurance swimming training (5 times/wk) in water at 33- 37℃ for 60 min. And they were divided into 2 groups according to the regular swimming training (control & trained). Analytical items were weight change, spleen index, total lymphocytes, and lymphocyte proliferation. All data were expressed as mean, standard deviation and SEM by using SPSS package program (win 10.0). The result through the statistical analysis of this data were summarized as follows; 1. In the weight changes, there was significant differences in Control & Trained following the swimming training. 2. In spleen index changes, there was significant differences in Control & Trained following the swimming training. 3. In total spleen lymphocytes, Trained group was much higher than that of Control. 4. In lymphocyte proliferation of splenocyte, there was significant differences in Control & Trained after Media, ConA and LPS stimulation.