Relevance. Ozone increases the oxygen transport function of the blood. The use of ozone therapy for pulmonary pathology is promising. The effect of ozone therapy is associated with the ability of ozone to eliminate hypoxemia and tissue hypoxia, which is always present in patients with pathology of the bronchopulmonary apparatus. Objective: to study morphofunctional changes in liver tissue, in the dynamics of the use of ozonized water in rats in an experimental model of chronic purulent pneumonia.Materials and methods. Three groups were formed from 30 male white rats (180-200 g). In group 1 (n = 10) healthy rats were injected intraperitoneally with 5 ml of ozonated (0.02 mg / L) 0.9% NaCl once a day for 10 minutes. Course 10 days. Animals of the 2 (n = 10) and 3 (n = 10) groups were first modeled for chronic pneumonia. For this, under local novocaine anesthesia, a 1.5-2.0 cm long incision was made on the animal's neck. A nylon thread with a diameter of 0.4 mm and a length of 10-12 cm was inserted into the lumen of the trachea, between its rings, on a thin piercing needle. The distal end of the thread was located in the lumen of the trachea, and its proximal end was fixed on the skin. The wound was sutured tightly in layers. After 45 days, the thread was removed without opening the trachea. Subsequently, animals of group 2 did not receive treatment. And rats of group 3 were injected once a day with 5 ml of ozonized (0.02 mg / l) 0.9% NaCl for 10 minutes. Course 10 days. The animals were removed from the experiment by instant decapitation. The taken pieces of the liver were fixed in formalin. Histological sections were stained with hematoxylin and eosin. Microscopy was performed using an XS-213 light microscope and a Leica microscope. Results. With prolonged irritation of the respiratory tract, structural changes in the liver, characteristic of toxic hepatitis, were revealed. After treatment with ozonated saline, the morphological picture of the liver improved. In healthy rats, ozone therapy did not have a negative effect on the general condition and behavior of the animals. Conclusions. Treatment with ozonated saline improves the morphological picture of the liver of rats with chronic pneumonia.