A complex prospective clinical and biochemical study was carried out in a group of 252 children with perinatal encephalopathy in dynamics during the 1st year of their life. The state of the lipid peroxidation (LPO) process, antioxidant system, and the phospholipid content of thrombocyte membranes were studied. Activation of the LPO process and a decrease in the antioxidant resistance level were observed. The efficacy of the antioxidant drug mexidol in infants was investigated for intravenous drug administration in a daily dose of 0.1-0.2 ml/kg over a 10-day period. The results confirmed good efficacy of the antioxidant therapy with mexidol in children with perinatal CNS disturbances.