[en] The effects on human erythrocytes of water-derived radicals generated by X-rays were studied under anaerobic conditions and in the presence of oxygen. Erythrocyte damage was estimated on the basis of the reduced GSH and MetHb content in the erythrocytes, the -SH group content in the membrane proteins and the amount of K⁺ released from the erythrocytes. The results obtained show that the level of reduced GSH was the most sensitive indicator of erythrocyte damage by X-rays followed by the efflux of K⁺ . The processes of GSH oxidation took place most rapidly under air. At a dose of 100 Gy, the level of GSH fell to about 50%, whereas under argon and N₂O to about 75% and 65%, respectively. A slight increase in the efflux of K⁺ was observed in preparations irradiated under air. However, when erythrocytes were irradiated under argon and N₂O, the loss of K⁺ occurred at a dose 8-times higher. Changes in the remaining parameters occurred at considerably higher doses. On the basis of the results obtained one can say that oxygen is a factor increasing the toxicity of OH radicals towards erythrocytes; however, e^-_aq present in the system can cause a decrease in damage to certain cellular components. (author)