This study was conducted to estimate the heritabilities, genetic, phenotypic and environmental correlations among litter size, body weights at birth and weaning in swine. The data analysed were recorded from 2794 male pigs produced by 282 boars of Hampshire, Yorkshire, Landrace, Duroc and Crossbreed raised at Duk Won-farm in Inchon from 1983 to 1984. The results obtained are summarized as follows: 1. The least square means over all litters studied were 9.86±0.13 pigs at birth, 8.57±0.13 pigs at weaning. Crossbreed Yorkshire and Landrace tended to be larger than Hampshire or Duroc in both traits. 2. The least square means of body weight over all litters studied were 1.37㎏ at birth, 6.82㎏ at weaning. 3. The hetitabilities of litter size at birth and weaning and body weight at birth and weaning were 0.454, 0.379, 0.009, 0.156, respectively. 4. Genetic correlation between litter size at birth and at weaning was 0.694, between body weight at birth and weaning was 0.294. 5. Phenotypic correlation between litter size at birth and at weaning was 0.794 and between body weight at birth and at weaning was 0.288. 6. Environmental correlation between litter size at birth and at weaning was 0.649, and between body weight at birth and at weaning was 0.294.