The article is devoted to an experimental study of the effect of tobacco smoke and the effect of sodium nitrite on the background of tobacco intoxication on the body of rats of different age groups and to identify violations caused by these toxicants. It has been established that under the conditions of nitrite-tobacco intoxication, a more pronounced cytolysis of the cells takes place, which leads to a change in the permeability of the plasma membranes than in case of poisoning with only tobacco smoke. Immature rats were the most sensitive to the action of toxicants, in which the activity of membrane-dependent enzymes was more statistically significant (ALT activity in the serum increased 7,7 times, AST - 5 times, GGTP - 4,1 times, LDH - 1,8 times; p ≤ 0.05) at the end of the study. In the same group of rats, the highest percentage of permeability of the erythrocyte membrane was revealed, as indicated by its index (55,6% higher than normal, in mature animals 38% EII was higher than in intact control animals, in old ones - 54%). When using an antihypoxant, it was noted that mildronate significantly (p≤0.05) reduced the activity of indicator enzymes in the blood serum of rats during the whole experiment, and also led to a decrease in the erythrocyte index of intoxication in the blood of rats of all age groups. To confirm the obtained results, morphological studies of the organs of rats of different age groups were carried out after sodium was damaged by nitrite against the background of tobacco intoxication and the effect of the metabolic action of mildronate on them. The membrane-protective properties of mildronate have been proven, which makes it possible to use it in various pathologies accompanied by the development of cytolytic syndrome.