Abstract: Objective: To investigate the effects of pioglitazone on the insulin resistance in the muscle tissue.（ Methods: Forty-five） male rats were divided into 3 groups including control,high fat-fed and pioglitazone group.The control rats were fed with common diet.The high fat-fed group were fed with high fat diet containing 59% saturated free fatty acids.The rats of pioglitazone group were fed with 10mg·kg^-1·d^-1 pioglitazone with high fat diet.These items were detected after each group was fed for 11 weeks. Results: （1）The relative content of visceral fat,fasting glucose,serum insulin,serum cholesterol and serum triglyceride,insulin resistance index,triglyceride in muscle were significantly higher in high fat-fed group than those in the control rats,but the cholesterol in muscle was not obviously changed.The relative content of liver and muscle insulin receptor and muscle GluT4 were decreased in high fat-fed group compared with these in the control.（2） In pioglitazone group,the relative content of visceral fat,fasting glucose,serum insulin,serum cholesterol and serum triglyceride,insulin resistance index,triglyceride in muscle were significantly decreased.The relative content of insulin receptor in muscle and GluT4 in muscle were not obviously changed. Conclusion: The decreased deposition of triglyceride in the muscle tissue is the main effects of pioglitazone on the insulin resistance in rats.