A complex of the blood system characteristics and the concentrations of heavy metals (Cu, Zn, Cd, and Pb) in the liver of bank voles (Cl. glareolus) and red voles (Cl. rutilus) from background and industrial polluted areas were studied. Heavy metals were found to affect the structure of erythrocytes, the blood cell composition and concentration in the hematopoietic organs. The revealed differences between the blood system's responses of bank and red voles to pollution conditions are due to different levels of the pollutant accumulation in the body.