The silver fox. a seasonal breeder of great economic importance, has a low reproductive efficiency in Korea. This study was carried out to obtain the basic data about the reproductive physiology of the silver fox being raised in Korea. A total of 135 litter in 1987, of which 83 were raised at Taekwanryung (N: 38.5°, E:128.8°),52 were at Yangsan (N:35.5°, E:129.0°), were used for this study. The vixens breeding started on January 27 and continued until March 25. The mode and mean was March 5 with an standard deviation of 18 days for vixens raised at Taekwanryung, while the breeding of vixens raised at Yangsan began February 16 with a standard deviation of 11 days. The mean date for mating of yearling was about a fortnight later them that of vixens of two and more than two of age which were all raised in two areas. The linear model was used to measure the effect of raising region, parity and the date of mating on litter size. The mean litters were 4.78±0.14 kits. The difference in litter size among 2 raising area, 2 parities and 4 dates of mating was not significant. However, the vixens raised in southern area, having the first parity and mating between March 1 and March 15 had more kits per litter than in the northern area, the 2nd parity and the other dates of mating.