Two groups of 20 bulls and 20 steers averaging 9Mo. of age(10 supplemented with yeast culture, YCS and 10 control, C in each group) were used to determine the effect of yeast culture supplementation on growth and carcass traits in Korean cattle. Yeast culture add to diet 20g/d/head during 11∼13Mo. and 15 -17Mo. and 25g/d/head during 20∼22Mo. of age in YCS. Weights at 26Mo. of age were 604.1±16.5, 592.7±16.5 and 538.0±13.5, 515.6±13.5Kg in YCS and C in bulls and steers, respectively. YCS had 1.9% and 4.3% advantage in weight over in bulls and steers. YCS did not affect meat quality grade but affect yield grade in bulls. In contrast, YCS in steers did not affect yield grade but were 5.7㎠ larger in longissimus dorsi area(YCS : 70.5㎠, C : 64.8 ㎠) and 273,138 Won higher in price per head than the counterparts. It appears that the effect of yeast culture supplementation was great in steers but not in bulls.