The purpose of this study was to assess 1)the effectiveness of the curved rear balance shoes in reducing knee pain in patients with knee osteoarthritis(OA) and 2)changes in EMG signal and strength of quadriceps muscle and physical function(ability to react instantly) compared with normal shoes for 8 weeks. The research design was a randomized controlled trial(24 female, knee OA grades Ⅱ-Ⅲ of radiographic evaluation). Subjects were randomized to curved rear balance shoes(n=14) or normal shoes(n=10). The mean IEMG, WOMAC(Korean Western-Ontario & Mcmaster) index questionnaire, peak torque with isometric training system at 90°/s, 150°/s and ability to react instantly were quantified at week 0 and after week 8. Paired t-test(for IEMG) and Repeated measurement design were done for between-group comparison(a=.05). There was a significant increase in average IEMG for quadriceps muscle in the curved rear balance shoes compared with normal shoes. There was an increase of average peak torque but no significant increase in muscle strength over the 8 wks. A knee pain and stiffness in knee after 8 weeks in the curved rear balance shoes was significantly reduced(p<.05). The ability to react instantly was increased but it’s not significant statistically. This result shows that wearing the curved rear balance shoes for 8 wks can reduce pain but it doesn"t make people who suffer from knee OA increase quadriceps for muscle strengthen.