The experiment on guinea pigs showed that an allergic alveolitis (AA) is accompanied by disturbance of prooxidant and antioxidant systems’ functional condition. In experimental AA the dienic conjugates and malonic dialdehyde contents increase, and the activity of catalase, peroxidase and ceruloplasmin decreases in mesenterial lymphatic nodes. Antioxidant correcting action upon the pointed out indices, in case of AA is revealed.