Nitrobenzene, o-nitrochlorobenzene and p-nitrochlorobenzene were studied in experiments with rats for their effect on intensity of lipid peroxidation (LPO), antioxidative activity (AOA), vitamin E content in the spleen and liver tissues as well as on certain hematological parameters of animals. These substances, when applied in acute experiments, deteriorate hematological parameters, intensify LPO in the spleen tissues. In this case AOA and vitamin E concentration grow. Subchronic action promotes stabilization of the studied parameters, which testifies to active adaptation of the organism to action of the above xenobiotics, as well as to high significance of the antioxidative homeostasis regulation system in the process.