Objective. To determine the optimal duration of energy corrective treatment of ischemic stroke (II) with cytoflavin or ascorbic acid. Material and methods. A multicenter randomized clinical trial included 185 patients, aged 40-75 years. Patients were randomized into 3 groups: the control group (n=64) received ascorbic acid; cytoflavin group 1 (n=72) was treated for 10 days and cytoflavin group 2 (n=49) for 20 days. In all groups, mean NIHSS score was 13, 42.2% of patients scored 14 and on admission, 42.2% of patients had consciousness impairment of different severity. Results. Cytoflavin treatment was more efficient than ascorbic acid that can be explained by different pharmacologic mechanisms. Treatment with cytoflavin for 10 days resulted in a significant decrease of ischemia zone volume by 25.2%, treatment with cytoflavin for 20 days - by 29.0%, which was associated with better outcomes in neurologic and functional status. Ascorbic acid demonstrated no effect on morphologic parameters. Prolonged treatment with cytoflavin in critically ill patients led to significant improvement in clinical and morphologic variables compared to the 10-day course. In patients with less severe condition comparable results were obtained. Conclusion. Our data justify the need for personalized integrated antioxidant and energy correction therapy.