Introduction of the cadmium chloride water solution to experimental animals induces changes in biochemical parameters which characterize structural and functional activity of transcriptionally active and repressed chromatin fractions. In the intoxicated chromatin-active fraction the DNA/protein ratio increases and DNA-polymerase alpha-activity decreases while in repressed chromatin activity of RNA polymerase I decreases as compared with controls. Change in intensity of lipoperoxidation reactions may underlie the cadmium chloride genotoxicity. This thesis is proved by an augmented level of NADPH-induced lipoperoxidation in active chromatin fraction.