PURPOSE The aim of this study was to investigate the effects of 12-week instrumental pilates exercise on isokinetic muscle function and body composition of healthy college women.METHODS Twenty-four college women (aged 21.6±1.3yrs) were recruited to the study. The participants were divided into two groups, as the instrumental pilates group (IPG, n=12) and the control group (CG, n=12). The springboard pilates exercise was conducted 3 times a week for 40~60 minutes during 12 weeks.RESULTS There was significant interaction effects in the right knee and left · right elbow extensor muscles (60°/sec) and left knee flexor and right elbow extensor · flexor muscles (180°/sec)(p<.05, p<.01). There was no significant interaction effects in the muscle mass of the total body, trunk, arms, and legs (NS) and also in the serum growth hormone, insulin-like growth factor-I and 25(OH)Vitamin D (NS). Serum creatine kinase was significantly increased (p<.05). There was also no significant interaction effects in weight, body fat, serum total cholesterol, triglycerides, low & high-density lipoprotein cholesterol (NS).CONCLUSIONS These results suggest that although prolonged instrumental pilates exercise of healthy college women might be improving isokinetic muscle function, there is no increasing effect of muscle mass.