This study was carried out to investigate overall performances and to estimate the effects of environmental factors on body weight in Korean native cattle on the basis of the records obtained from 15,569 heads of Korean native cattle raised at Hanwoo purebreeding region from 1989 to 1995. Overall least squares means and standard errors of body weights at birth, 3, 12 and 24 months of age were 23.77±0.15, 79.91±1.25, 232.08±3.22 and 341.45±5.05㎏, respectively. The effects of the breeding region, generation, year of birth and registry class on the birth weight were highly significant. The effects of the breeding region, generation, year and season of birth, and registry class were significant on the body weight at 3 months of age. The effects of the breeding region, generation, year of birth and registry class were highly significant on the body weight at 12 mo. The breeding region, year of birth, season of birth and registry class had highly significant effects on the body weight of 24 mo. cattles(P$lt;0.01).