Objective To observe the effects of aspirin on insulin sensitivity in high fat fed rats. Methods Before and after ingesting aspirin, intraperitoneal insulin tolerance test was used to measure the insulin sensitivity, and fasting blood glucose, insulin and blood lipid were determined. Results Fat fed rats had similar glucose concentration to chow fed rats, but significantly higher levels of insulin, triglyceride(TG) and 1 h,1 5 h,2 h blood glucose concentration after intraperitoneal insulin tolerance test. Serum levels of insulin,TG and 1 h,1 5 h,2 h blood glucose concentration after intraperitoneal insulin tolerance test of fat fed rats treated with aspirin were significantly lowered. Conclusion It is confirmed that aspirin could raise insulin sensitivity of high fat fed rats.