The objective of the study was to determine the concentration profile of selected hormones in the blood serum of blue polar fox vixens at various ages during the non-mating period, three months after lactation. The investigation was performed on 50 clinically healthy female polar foxes derived from a domestic reproductive farm. The animals were divided into 5 age groups (n = 10) ranging from the 1 to 5 years of life. In the blood serum the contents of insulin, triiodothyronine (total and free), thyroxin (total and free), leptin and ghrelin (total and active) were determined. No significant, female age-dependent differences were found in the contents of insulin, total and free triiodothyronine and total ghrelin in the blood serum. Significant (P < 0.05) differences were observed in the concentration of total and free thyroxin (the highest in the blood of 4-year old females) as well as leptin and active ghrelin (the lowest and the highest content in 3-year old vixens). However, no distinct, female age-dependent tendencies for change in the content of these hormones in the blood serum were observed.