TThe studies conducted on a polar fox farm aimed to show the influence of the environmental factors on the cortisol secretion. A group of young weaned foxes maintained at the farm constituted the control, while the experimental group consident of the foxes born and separated from mothers, kept in the closed chamber of different microclimatic conditions. The cortisol values in the foxes from the control group were higher (6.77 μg/dl) compared to those in the experimental animals (4.59 μg/dl). These values indicate different responses of the foxes under investigation.