Strong positive correlations between selenium (Se) and total mercury (Hg _Ｔ) contents in the liver of marine mammals and mercury mine workers in modern times have been documented in numerous investigations. Herein, we report a positive correlation between Se and HgT concentrations over the past 1,500 years in the seal hairs and in the lake sediments amended by seal or penguin excrements on King George Island (63 ^。23 ^，S, 57 ^。00 ^，W), West Antarctica. Because the changes in the input of Se and Hg into the marine environments of the studied sites do not seem to be synchronous, this striking correlation indicates a selfprotection mechanism in Antarctic seals and penguins: Every time there is heavier Hg burden, more Se is accumulated to reduce the toxicity of Hg. This positive correlation between Hg and Se contents in the seal hairs and excrement sediments, however,becomes insignificant in the recent 50 years for unknown reasons.