Heritabilities and correlations between litter size and litter weight at birth and at weaning were estimated from paternal half-sib analyses on the basis of the data from 2,156 litters of purebred Landraces, Yorkshires, Durocs and Hampshires. The results obtained in this study are summarized as follows; 1. Heritabilities of litter size at birth and at weaning estimated were 0.20 ±0.09 and 0.11 ±0.08 for Landraces, 0.25 ± 0.12 and 0.14 ± 0.11 for Yorkshires, 0.04 ± 0.09 and 0.03 ± 0.09 for Durocs, and 0.12 ± 0.10 and 0.10 ± 0.10 for Hampshires, respectively. Heritability estimates of litter weight at birth and at weaning were 0.32 ± 0.11 and 0.11 ± 0.08 for Landraces, 0.32 ± 0.13 and 0.12 ± 0.10 for Yorkshires, 0.23 ± 0.13 and 0.08 ±0.10 for Durocs, and 0.09 ±0.10 and 0.03 ±0.08 for Hampshires, respectively. 2. The genetic correlations of litter size at birth with litter size at weaning and litter weight at weaning were 0.82 and 0.56 for Landraces, 0.76 and 0.49 for Yorkshires, 0.53 and 0.47 for Durocs 0.79, and 0.33 for Hampshires, respectively. The genetic correlations between litter size at weaning and litter weight at weaning were 0.92 for Landraces, 0.83 for Yorkshires, 0.74 for Durocs, and 0.73 for Hampshires, respectively. 3. The phenotypic correlations of litter size at birth with litter size at weaning and litter weight at weaning were 0.78 and 0.70 for Landraces, 0.75 and 0.65 for Yorkshires, 0.80 and 0.73 for Durocs, and 0.83 and 0.73 for Hampshires, respectively. The phenotypic correlations between litter size at weaning and litter weight at weaning were 0.88 for Landraces, 0.88 for Yorkshires, 0.91 for Durocs, and 0.91 for Hampshires, respectively