The purpose of this study investigated the effects of different intensities of eccentric resistance training on the numbers of natural killer (NK) cells and T cells. Twenty healthy male college students (age=20.2±2.1 yrs-old, ht=170.4±6.1cm, wt=72.3±12.2kg) were randomly assigned to one of the following two groups: group A-moderate intensity of eccentric resistance training (60°/sec, 32 rep) and group B-low intensity of eccentric resistance training (120°/sec, 32 rep). The blood samples were collected before. 10 minutes after. 24 hours after, 48 hours after, 72 hours after, 96 hours after, and 120 hours after the exercise in the two different groups. In group A, both the numbers of NK cells and T cells increased significantly at 10 minutes after training than those before training (p<.05). Besides, at 24 hours after training, the numbers of NK cells and T cells decreased significantly than those before training (p<.05). In group B, the numbers of NK cells and T cells also increased more significantly at 10 minutes after training than those before training (p<.05). At the other sessions of time, there were no significant differences in the numbers of NK cells and T cells compared with those before training. The result of this study suggested that low intensity of eccentric resistance training was suitable for everybody. However, although moderate intensity of eccentric resistance training might be effective transiently for the trained athletes, health care should be taken carefully.