The purpose of this research is to investigate the effect of swimming and treadmill training on the change of leptin, anti-oxidant enzymes and hormonal changes in rats. For this study, SD rats were divides into three groups: control group (COG: n=15), swimming trained group (ST: n=15), and treadmill trained group (TTG: n=15). The animals were housed in a pathogen-free animal facility (22-24℃, 44-45% relative humidity, 08:00-20:00 lighting hours) at K university college of medicine. The trained rats under went a 9-wk endurance swimming training (5 days/wk) in water at 24-27℃ (STG) and treadmill training (5 days/wk) in DAEJONG treadmill for 30 min. The result through the statistical analysis of this data were summarized as follows: In the weight changes, there were significant differences among COG, STG and TTG (p<.05) after regular swimming and treadmill training. In the cholesterol changes, For the STG and TTG, there were significantly decreased after regular swimming and treadmill training than COG(p<.05). In the anti-oxidant enzyme changes, For the STG and TTG, there were significantly increased after regular swimming and treadmill training than COG, STG was the hightest. In the leptin changes, For the STG and TTG, there were significantly decreased after regular swimming and treadmill training than COG, TTG was the lowest. In the insulin changes, For the STG and TTG, there were significantly decreased after regular swimming and treadmill training than COG, STG was the highest. In the cortisol changes, For the STG and TTG, there were significantly decreased after regular swimming and treadmill training than COG, STG was the highest. Therefore we can conclude that regular swimming and treadmill training prevent obesity which is caused by reduced body weight, cholesterol, and leptin hormone.