The aim of the study was to determine the activity of glutathione reductase (GR, EC 1.6.4.2) in the blood serum of patients with alcoholic hepatitis (AH) and in the blood serum and livers of rats with experimental toxic hepatitis (ETH), as well as to develop a scheme for the purification of the enzyme from the liver of experimental animals using chromatographic methods. In the experiment, we used the blood serum of apparently healthy individuals with normal indices of general and biochemical blood tests (control group of patients), people diagnosed with alcoholic hepatitis (AH), as well as the serum and livers of rats in the control group and rats with ETG. The pathological state in experimental animals was modelled by oral administration of carbon tetrachloride, an organ-specific toxin with hepatotropic effect, as a 33% solution in paraffin oil at the rate of 64 µl of toxin per 100 g of animal weight. The animals were slaughtered on the 4th day after administration of the toxic agent. The control animals were injected with the corresponding aliquot of paraffin oil. The activity of GR was determined spectrophotometrically using a spectrophotometer SF-46 at a wavelength of 340 nm. The total amount of protein was determined by the Lowry method. To study the regulatory properties of the enzyme, it was purified from the livers of the control rats and those with induced toxic hepatitis using the protein separation by ammonium sulphate, as well as gel filtration through Sephadex G-25 and ion-exchange chromatography on DEAE-cellulose. As a result, we obtained 54.5 and 49.1 times purified GR enzyme preparations from the livers of the control rats and animals with ETG. We determined that in the process of ion-exchange chromatography using a column with DEAE-cellulose, the enzyme from the livers of the studied groups of animals was desorbed as a single peak at a KCl concentration of 100 mM. Using the obtained enzyme preparations, we detected differences in the regulation of GR activity under the action of Krebs cycle intermediates. They are obviously associated with conformational modifications of the enzyme molecules under oxidative stress developing during pathology.