The aim of this study was to determine the effect of resistance training for 10 weeks on muscle strength, lean body mass, serum myostatin, and insulin resistance in obese-overweight men. Seventeen obsess-overweight men(age:=43.1±4.7 yr, body mass index = 29.1±2.17 kg/m2) participated in the study The subjects were randomly assigned to resistance training (n=9) and control (n=8) groups. Resistance training was performed 3 times weekly for 10 weeks. Body composition, metabolic parameters, and myostatin were measured prior to and after the intervention. After a 10 week resistance training, insulin resistance index (HOMA-IR) was significantly decreased (P<0.05), but without changes in adiposity parameter such as body weight ,body mass index, fat percent and waist circumference (P>0.05). Also, following the resistance training, muscle strength and lean body mass were significantly increased (P<0.05). Concurrently, myostatin concentration were significantly decreased in response to resistance training (P<0.05). In conclusion, this study demonstrate that 10 weeks of resistance training caused an improvement in insulin resistance in obese-overweight men, independent of changes in body fat, and this improvement was associated with decreased myostatin levels. These data suggest that resistance training – induced alterations in myostatin levels may have role in resistance training – induced insulin sensitivity improvement.