This experimental study was designed to investigate the effects of Yukgunja-tang(YGJT) on the change of weight and serum total cholesterol, HDL-cholesterol, LDL-cholesterol, triglyceride, free fatty acid, total lipid, phospholipid level in obese mice induced by high fat diet. I fed normal group fed normal diet and administered DDW 0.2㎖ during 7 weeks, control group fed high fat diet and administered DDW 0.2㎖ during 7 weeks, sample A group fed high diet and administered YGJT 300mg/kg 0.2㎖ during 7 weeks, sample B group fed high diet and administered YGJT 500mg/kg 0.2㎖ during 7 weeks. The results were as follows ; 1. Sample A and Sample B were significantly decreased body weight(4weeks) and serum free fatty acid level in comparison with control group. 2. Sample A was significantly decreased body weight(7weeks), serum total cholesterol level and serum total lipid level, but significantly increased serum HDL-cholesterol level in comparison with control group. 3. Sample A was decreased serum LDL-cholesterol level, serum triglyceride level and serum phospholipid level in comparison with control group. 4. Sample B was increased serum HDL-cholesterol level in comparison with control group. 5. Sample B was decreased body weight(7weeks), serum total cholesterol level, serum LDL-cholesterol level, serum triglyceride level, serum total lipid level and serum phospholipid level in comparison with control group. According to above results, I suggest YGJT is able to be used for the herbal medication of obesity.