The measurement of levator muscle function is very important in the evaluation of blepharoptosis and in the choice of surgical method for blepharoptosis. And these functional values of levator muscles are very helpful in case of being operated on bilateral ptosis. There are two methods in measuring the levator muscle function. Most popular one is Berke's mehtod and the other one is margin limbal distance. The levator muscle function is the most important factor to determine the method of treatment of bleparoptosis. The normal values of levator muscle functions are variable according to races, sex and ages. Unfortunately, there are few articles concerning them in Korea yet. So, we have inevitably utilized the Caucasian or Japanese statistical data in blepharoptosis surgery. Authors measured the levator muscle function by Berke's method and margin limbal distance in Koreans, and statistically analyzed them in 498 individuals including 234 males and 264 females. The results were recorded as follows: 1.The mean values of levator muscle function was 11.9+/-1.6mm in males and 11.9+/-1.6mm in females by the Berke's method, and it was 6.5+/-1.0 mm in males and 6.6+/-1.0mm in females by margin limbal distance. 2.No statistical difference was in males and females, in left and right levator muscle function. 3.The levator function reached the peak level at high teenagers and twenties in a great portion. After the peak level, the changing pattern of levator function was stationary or decreasing gradually.