The purpose of this study was to estimate the heritabilities, genetic and phenotypic correlations among certain economic traits on the basis of the data from 490 heads of Korean Native Cattle tested at the Korea Native Cattle Improvment Centre at Seosan, Chungnam Province from August, 1985 to October, 1987. The traits studied were body weights, average daily gain, feed efficiency and carcass traits. The results obtained are as follows. 1. The heritability estimates of the body weights were 0.15±0.033 at birth, 0.20±0.034 at weaning, 0.34± 0.042 at 6 months of age, 0.20±0.035 at 9 months, 0.21 ±0.031 at 12 months, 0.24±0.037 at 15 months and 0.14±0.033 at 18 months of age, respectively. The heritability estimates of the average daily gains for each period of 3, 6, 9 and 12 months after testing were 0.16±0.034, 0.18±0.036, 0.11±0.031 and 0.19±0.035, respectively. 2. The phenotypic correlations among body weights at different ages were positive ranging from .096 to .69.698. The genetic correlations of 12 month weight with body weights at birth, weaning, 6 months and 9 months of age were .649, .276, .751 and .596, respectively. The phenotypic correlations between backfat thickness and body weights after weaning ranged from. .107 to .295. The genetic and phenotypic correlations between dressing percentage and body weights at different ages were low. The phenotypic correlations between retailed cuts and body weights after weaning ranged from -.084 to -.250. The genetic and phenotypic correlations between cutability and body weights at different ages were low. The phenotypic correlations among average daily gains for 3, 4, 5, 6, 7. 8 and 12 months ranged from .382 to .768. The gentic correlations of average daily gains with weaning weight or with 15 month weight were negative, but those with birth weight were positive.