Accumulation of heavy metals (Cu, Zn, Cd) in hemopoietic-competent organs of ecologically contrast species of small mammals (Clethrionomys glareolus, Sorex araneus, Apodemus uralensis) from natural populations of the Middle and South Urals were considered. The content of exogenous and essential trace elements in animal tissues (a liver, kidney, a spleen) was determined by atomic absorption spectroscopy. It has been shown that bioaccumulation of heavy metals in organs of insectivores significantly differs from it of bank voles and wood mice. The smallest total content of heavy metals is shown in wood mice in technogenic territories of the Middle Urals. The submitted data demonstrate the competitive mechanism of the Cu, Zn, Cd. The increased concentrations of endogenous trace elements (copper, zinc) in relation to a toxicant (cadmium), other things being equal, reduce cadmium accumulation level in the tissues Sorex araneus.