Since it is still absent data about the toxic risk of low dose, especially an environmentally relevant dose of mercury to fetus after their prenatal exposure, this present work was designed to investigate the metabolism of Hg and its effect on the levels of essential trace elements in the organic tissues and the brain regions of infant rats after their exposure to environmentally relevant low dose of Hg(II) during the whole pregnant and weaning period. The pregnant female rats were exposed to a very low dose of 0.2gHg2+/ml (as HgCl2, 12 rats/group) in drinking water from prenatal day 0 continued to postnatal day 20. The contents of Hg and other elements (Cu, K, Mg, Mn, Na, Ca, Co, Fe, Se and Zn) in the liver, kidney, heart, spleen, pancreas and the brain regions (cerebrum, cerebellum, brain stem, hippocampus, thalamus and the remains) of the maternal and their infant rats were determined. The highest Hg contents were found in kidney of both maternal and infant rats. Considering the percentage of Hg accumulation, approximately 52.7%, 38.7%, and 1.66% were found in kidney, liver and brain for maternal rats, respectively, while 23.7%, 48.9% and 15.6% for infant rats. The important findings in this work were that the low dose of inorganic mercury appeared to accumulate in the brain of offspring and more Hg was present in infant brain than in their mother. As in the brain regions, the highest Hg content was present in infant hippocampus and cerebellum, whereas the Hg contents in maternal brains varied not so much. The imbalances of Fe/Cu, Cu/Zn, Zn/Se mass ratios and the molar ratios of Hg over other elements in the Hg-exposed rats were observed.