This study was conducted to determine the main effects and interactions of breed, furrowing season and parity on swine reproductive traits: litter size at birth and weaning, pig and litter weight at birth, 21 days and weaning on the basis of the data obtained from 1047 litters of Berkshire and Landrace born from 1976 to 1980 at Sacheon Branch, National Livestock Station. The data were analysized by the least square method and results obtained are summarized as follows: 1. Landrace was heavier by 10% in litter weight at weaning, 17% in litter weight at 21 days, 10% in litter weight at birth, 23% in pig weight at 21 days than Berkshire. 2. The effect of breed for each litter weight and pig weight at 21 days was highly significant at 1% level. 3. The effect of furrowing year was highly significant for all the traits studied without any consistent pattern as the year passed. 4. The reproductive performance of the pigs born in the spring was significantly higher (p$lt;.001) than that in the fall except for the pig weight and litter size at weaning. 5. The litter size at birth or weaning was significantly larger (.1%) in the groups of the 2nd to 6th parity than in the other groups. All the body weight traits studied were significantly (.1%) superior in the 2nd 4th, the 5th - 6th, the 7th and over, and the 1st parity in that order. 6. The pig weight at weaning in Berkshire was significantly heavier in the spring-born group. The litter size at weaning and litter weight at birth in Landrace was significantly higher in the spring-born groups than in the fall-born ones. 7. The effect of breed x parity interaction was nonsignificant for the traits studied.