The aim of the study was to determine the factors (mating season, the herd, parity, and boar) that influence litter size in Banija spotted pig population. The study was conducted on 298 farrowing records from 136 Banija spotted sows collected between 2014 and June 2019 at several herds in the area of Banovina and its surroundings. Statistical analysis revealed statistically significant effect of the farrowing season, herd, and parity, while the impact of boar was not statistically significant. After statistical analysis, a gradual increase in the number of live piglets was observed after each subsequent farrowing until the fifth parity. The effect of the season is manifested through short-term (climate) and long-term (changes in production technology) changes in litter size. Significant differences in the number of liveborn piglets between herds were found, indicating differences in technology and production conditions. The differences range from 4 to 6 piglets per litter. In the future, the fertility of the Banija spotted pigs should be improved in order to obtain more litters with a larger litter size, which may positively affect the breeding efficiency of this breed. The results obtained indicate a high variability in the number of live piglets in pig swine.