Introduction. Serous meningitis takes a leading place among the central nervous system lesions, the share of which in neuroinfections structure ranges from 25 to 70 %. The imbalance in the functioning of prooxidant-antioxidant system plays a leading role in the damage of the nerve cells and leads to their death. Objective. To explore indicators of prooxidant-antioxidant regulation in the dynamics of the disease in patients with serous meningitis. Materials and methods. We observed 64 patients with serous meningitis at the age of 18 to 74 years old. Spectrophotometric method was used to determine the blood serum stable metabolites of nitric oxide — nitrites, spontaneous performance and metal-catalyzed oxidative protein modifications and catalase activity in the patients with serous meningitis. The control group consisted of 30 healthy individuals. Results. In the patients with serous meningitis at admission on the background of the dominance of clinical signs of general intoxication, cerebral, meningeal syndromes there were increased (p < 0.0001) indicators of spontaneous and metal-catalyzed oxidative modification of protein, nitrite, in combination with low (p < 0.0001) catalase activity in serum compared to healthy individuals. At the beginning of the second week of the treatment of the patients with serous meningitis the certain regression of clinical symptoms was accompanied by a deepening imbalance of indicators of prooxidant-antioxidant regulation towards the process of free-radical oxidation, which remained at discharge from hospital. Conclusions. In the patients with serous meningitis on admission there was revealed the imbalance of the indicators of prooxidant-antioxidant regulation, which deepened on the second week and remained during the standard treatment till the discharge from hospital.