The article presents research results on total mercury distribution and bioaccumulation in organs and tissues of Baikal seal of different ages. The research demonstrates effective mercury elimination through the hair coat. Hg bioconcentration level in the seal liver was shown to be maximal as compared with other elements. Most important biological factors, those affect Hg concentration level in liver, are sex and age of the Baikal seal. Hydrobionts of the Baikal pelagic chain are shown to have a low Hg concentration level. The highest Hg bioaccumulation rate is observed at the upper trophic levels (fish-seal).