The purpose of this study was to examine the isokinetic moment of quadriceps and hamstring strength ratio among women of different ages. The study population consisted of 1,184 women referred to the Health Promotion Center at the S district. All subjects were aged 20 to 69 years old and divided into 5 groups; 20s (n=248), 30s (n=255), 40s (n=248), 50s (n=228), and 60s (n=205). The strength of the knee extensor and flexor, quadriceps, and hamstring of all the participants were assessed at 60 degrees/second with an isokinetic machine. We calculated the peak torque, peak torque %BW (%Body Weight), deficit of peak torque and hamstring/quadriceps ratio of the knee. The data were analyzed by one way ANOVA to investigate statistical differences in strength variation between different age groups and were computed by ⊿% difference from women in their 20's. The results were obtained as follows: 1. Peak torque of the knee extensor, quadriceps, were significantly reduced in women older than 30, but peak torque of the knee flexor, hamstring, were significantly reduced in women older than 50 compared to women in their 20's. (p<.05). 2. Peak torque %BW of the knee extensor, quadriceps, were significantly reduced in women older than 20, but peak torque %BW of knee flexor, hamstring, were significantly reduced in women older than 40 compared to women in their 30's (p<.05). 3. Compared to the women in their 20's, there was no significant difference among any of the age groups in the deficit of peak torque of the knee extensor and flexor, but the deficit of peak torque of knee extensor among women between 30 and 50showed significant difference within the normal range of deficit. 4. Compared to the women in their 20's, there was no significant difference among any of the age groups in the hamstring/quadriceps ratio These results showed that peak torque, peak torque %BW, deficit of peak torque, and hamstring/quadriceps ratio of the knee were reduced in each age group, but especially among the women over 50. Further longitudinal study may be needed to see if volume of muscle mass and intervention of exercise affect knee strength in spite of aging.