The aim of the study was to determine the values of selected haematological and biochemical parameters in peripheral blood of female polar fox in relation to the age of the animals. The research involved 50 polar fox females three months after the lactation period (i.e. the non-mating period). Animals were divided into 5 age groups (n = 10), ranging from 1 to 5 years of age. In blood samples the following parameters were determined: RBC, Ht, Hb, WBC, PLT, red blood cell parameters (MCV, MCH, MCHC) and the percentage of respective kinds of white blood cells in the total number of leukocytes. The content of Ca, Pi, Na, K, Cl, Mg, Fe, Cu and Zn as well as the ALP and ACP activity was determined in blood serum. In comparison with one year-old females, in peripheral blood of females from the remaining age groups an increase in RBC, Ht and Hb content was observed as well as a significant (P < 0.05) decrease in WBC level together with a lower number of lymphocytes and an increase in the relative content of granulocytes and monocytes. No distinct relationship between the content of Ca, Na, Cl, Mg, Cu, Zn, the activity of ALP and ACP and the age of the animals was observed. The highest concentration of Pi and K was found in the blood serum of one year-old females. The content of Fe decreased with age and was lowest in 5 year-old animals (P < 0.05).