The objectives of these studies were to investigate the growth performances and to estimate heritabilities for body weight and average daily gain of Aberdeen Angus and Charolais males bred for 10 years in Cheju. Results are as follows: Overall least squares means of body weight at birth and ages of 6, 12 and 18 months were 24.8, 111.7, 221.0 and 409.6㎏ in Angus; 31.2, 134.4, 269.7 and 449.2㎏ in Charolais, respectively. Least squares means of average lifetime daily gains from birth to 6, 12 and 18 months of age were 0.477, 0.535 and 0.708㎏ in Angus; 0.577, 0.658 and 0.765㎏ in Charolais, respectively. Estimated heritabilities for body weight at birth and ages of 6, 12 and 18 months were 0.34, 0.18, 0.17 and 0.21 in Angus; 0.24, 0.18, 0.30 and 0.21 in Cha-rolais, respectively. Heritability estimates of average daily gain at 6, 12 and 18 months of age were 0.20, 0.19 and 0.18 in Angus; 0,11, 0.28 and 0.20 in Charolais, respectively.