The results of a crossbreeding experiment with a total of 315 litters of Berkshires, Hampshires, Durocs, Landraces, Large Whites; eight different two-breed crosses and twelve different three-breed crosses, produced at Livestock Experiment Station from 1975 through 1979, are summarized as follows. 1. Number born alive per litter was largest in the D♂×(Lw♂ × L♀) F₁♀ mating, followed by the D♂ × (H♂ × L♀) F₁♀ mating, and was smallest in the Hampshires. The pigs in the 3rd-6th parities had larger litter size at birth than those in other parities. 2. Birth weight of pig was heaviest in L♂ × Lw♀ mating and lightest in the Large White. The total litter weight at birth was heaviest in the D♂ × (Lw♂ × L♀) F₁♀ mating, followed by D♂ × (H♂ × L♀) F₁♀ and Lw♂ × L♀ mating, and was smaller in Hampshires and Berkshires. 3. Latter size at weaning was largest in the D♂× (Lw♂ × L♀) F₁♀ mating, followed by D♂× (H♂×L♀)F₁♀ and Lw♂ × L♀ matings, and was smaller in Durocs and Hampshires. The pigs in the 3rd-6th parities had larger litter size at weaning than those in other parities. 4. The total litter weight at weaning was heaviest in the D♂ × (Lw♂ × L♀) F₁♀mating, followed by H♂ × (Lw♂ × L♀) F₁♀ and Lw♂ × L♀ matings, and was lighter in Durocs and Hampshires. The weaning weight of pig was largest in D♂ × (Lw♂ × L♀) F₁♀ mating and lightest in L ♂ × H♀ mating. 5. Survival rate at weaning was hightest in L♂ × Lw ♀ mating, followed by D♂ × (L♂ × H♀) F₁♀ and D♂ × (H ♂ × I ♀) F₁♀ matings, and was lowest in Durocs. 6. The results obtained in this study suggest that the two-breed cross from Lw♂ × L ♀ mating, and the three-breed crosses from D♂× (Lw♂ × L♀) F₁♀ and D ♂ × (H♂× L♀) F₁♀ matings are superior crossbreds for reproductive performance.