This study was carried out to investigate the effects of the environmental factors on economically important traits of Korean Native Cattle. The traits studied were body weight, body length and chest girth. Data used for this study included the record of a total of 986 heads of Korean Native Cattle raised at Alpine Experiment station located in Kangwon province from 1974 to 1988. The results obtained in this study were as follows ; Overall least square means and standard errors for body weight of the bull at birth, 6, 12 and 18 months of age were 25.9±0.18, 130.9±1.01, 322.1±1.74 and 453.2±3.20㎏, respectively. The body weights of heifers were 23.9±0.21, 112.9±1.44, 175.3±2.34 and 229.0±3.31㎏, respectively. The least squares means and standard errors for body length and chest grith showed the range of 57.4±0.23∼142.9±0.46 and 68.2±0.22∼184.2±0.59㎝ through overall months of age in bulls, respectively. Those computed from the female showed the range of 56.2±0.33∼118.9±0.59 and 66.6±0.29∼146.7±0.78㎝, respectively. The effects of year of birth showed significant differences for most of traits. The effect of season was significant for body weight at 12 and 18 months of age in bulls, body weight at 6 months, body length at birth, 6 and 12 months and chest girth at 6 months of age in heifers. The parity effects were significant only for body weight at 12 months of age in heifers and chest girth at 12 months of age in bulls. The effect of dam age was not significant for body weight at 18 months in bulls and 12 months in heifers and was not significant for chest girth at birth in bulls and chest girth at birth, 12 and 18 months in heifers.