The research aimed at the analysis of influence of birth term and females' age on the reproduction results of common silver foxes (Vulpes vulpes L.). The data included 1155 litters in the years 1997-2003. The analysis of variation for the number of born foxes proved statistically significant influence of the calendar year. In relation to the number of raised animals, it has been proved that the females' age was statistically significant. No statistically significant impact of the whelping season on the analysed traits was noted. The mean number of born puppies was the lowest in one year old vixens (4.36 individuals) and six years old (4.30), while the raised in one year old vixens (3.85 individuals) and two years old (4.07). The highest values were obtained by five yeas old females (4.85 and 4.66, respectively). As far as the whelping season is concerned, little impact on reproduction results was noted. Litters in the earlier births (births up to 10th April) were more numerous (4.49 born and 4.10 raised) in comparison to the late kittenings of females (births in May), (4.24 and 4.01, respectively). The number of born pupies per litter ranged from 1 to 8 animals while the number of raised ranged from 0 to 8 animals. Over 27% of vixens delivered 5 puppies, 22% delivered 4 puppies and 15% delivered 6 puppies. Variability of traits estimated by variability coefficient ranged from 30 to 35% for the number of born and from 30 to 50% for the number of raised animals. The obtained results of the reproduction seem to be very good.

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