Three different methods of adjusting the weaning weight to an age-constant basis were evaluated on the basis of the data from 6,414 heads of Hanwoo raised at the Hanwoo Improvement Center, National Livestock Cooperatives Federation in Seosan, Chungnam from 1990 to 1998. Methods 2 and 3 which utilize the quadratic regression models for the adjustment were superior to Method I which adjusts the weaning weight based on the average daily gain from birth to weaning. The best method of adjustment appears to be the Method 3 which adjusts by the quadratic regression model the weaning weight preadjusted by Method 1, taking into account the growth rate to weaning.