Lipid peroxidation (LPO) has been studied in patients with influenza complicated by pneumonia as shown by GPL and MDA serum levels of GPL and MDA. Acute period of the disease was characterized by a sharp rise in LPO products production, especially in seriously ill patients. Administration of alpha-tocopherol promoted a significant decrease of MDA and GPL levels and more apparent clinical response. Dibunol caused minimal changes in the disease clinical pictures and LPO activity.