The purpose of this study was to investigate the relationship between plasma leptin and %BF, insulin sensitivity, plasma lipids after exercise endurance training. Rats were assigned to one of two experimental groups based to run on a motorized treadmill: 1) sedentary control (CON, n=10), 2) exercise training (Ex, n=30). The exercise training protocol used in this study consisted of running on motor driven treadmill up an 8% grade, 5 days/week for 8 weeks. The training speed and duration was 27m/min, 90min. Both treadmill speed and duration were rapidly increased during the first few weeks of training, such that the rats were running 90min at 27 m/min by the end of the second week. After 8-weeek treatment, Ex was significantly lower in plasma leptin levels than in CON (CON; 5.52±0.54, Ex: 1.24±0.24 ng/㎖). %Body fat of CON was significantly higher than Ex (CON: 12.45±0.23, Ex: 8.02±0.38 %). During the OGTT, plasma insulin levels in Ex was significantly lower than in CON, but not glucose levels. The TC, HDL-C level in Ex was significantly lower than in CON, but TG levels was not different among groups. Summary, Compared with CON, Ex revealed significant decreases in %BF, resting plasma insulin, leptin, TC, TG and significant increase in insulin sensitivity. But the relationship between plasma leptin with %BF was R2=0.82, with insulin was R2=0.4036, with lipids was R2=0.3221 (TC), R2=0.4112 (TG), with insulin sensitivity (R2=0.4036). Therefore this results suggested that the change in plasma leptin levels in only related with %BF.