. Main genes determining white coat colour in Arctic foxes are: recessive gene d and incompletely dominant, autosomal gene S with lethal effect in homozygous condition. The white coat colour of Arctic foxes bred on Polish farms had been determined solely by the recessive gene until the 1970s, when the Shadow variety was imported from Norway. The genetic code of the two varieties was different, but this fact was not taken into account. The results obtained in the present study do not confirm the theories on the heredity of white coat colour of Arctic foxes. The authors of these theories assumed that the coat colour depends on the presence of a recessive gene, the only factor responsible for the white furcoat. Apart from Polar and Shadow white foxes, there is a wide variety of darker white animals, and this fact suggests that there is a number of cumulative genes responsible for the intensity of coat pigmentation.