This study involved the records of 389 heads of Duroc, Hampshire, Large Yorkshire and Landrace boars tested at National Breeding Institute from 1980 to 1987. The Purpose of this analysis was to investigate the relationship between preweaning traits and postweaning traits. Preweaning and postweaning traits studied were; the number of live pigs in the litter in which the boar was born(LSBNA) and weaned(LSWN); his birth weight (BW), weight at 21days of age(GW21D), Weaning weight(WW56D); average daily gain(ADG), backfat thickness (BFT), feed Requirement(F/R), the days to 90㎏(90DAYS), IOWA-INDEX(INDEX). The heritabilities and genetic and phenotypic correlations were estimated from the sire components of variance and covariance. 1. Heritabilities estimated were 0.521±0.188(ADG), 0.219±0.169(F/E), 0.459±0.181(BFT), 0.91±0.215(90 DAYS), 0.337±0.173(INDEX), 0.371±0.312(LSBNA), 0.261± 0.191(LSWN), 0.174±0.153(BW), 0.208±0.157(GW21D) and 0.268±0.163(WW56D), respectively. 2. Genetic correlation of performance index (INDEX) with (BW), (GW21D), and (WW56D) were 0.326, 0.460 and 0.169, respectively, Phenotypic correlation of (INDEX) with (BW), (GW21D) and (WW56D) were 0.145, 0.065 and 0.076, respectively. Genetically (BW), (GW21D) and (WW56D) of the preweaning traits tended to show positive relationship with postweaning traits. These result indicated that the better growth rate at early stage tended to have a better performance.