The levels of mercury and selenium and their correlation in scalp hair samples of 29 pairs of women and their newborn children living at a high-Hg and low-Se area the Second Songhuajiang River System have been studied by instrumental neutron activation analysis. Our results indicate that the Hg level in infant hair samples roughly equals to that in their mother’s

while the Se level in infants is much higher. The molar ratios of Se/Hg in baby’s hair are also 40% higher than those in mother’s. It is demonstrated that infant is able to absorb more selenium from mother’s body to protect from or alleviate the intoxication of mercury. The autoprotection mechanism likely plays an extremely critical role during the development stage of foetus.