Objective: To study the efficacy and safety of early use of mexidol in the acute stage of severe ischemic stroke (IS). Material and methods: A study included 112 patients, aged from 35 to 85 years, with a severe IS. Patients were stratified into two age and sex- matched groups. The main group (n=59) received mexidol in dose of 500 mg daily intravenously during 10 days in addition to standard treatment. The comparison group (n=53) received standard treatment only. Results: In the main group, the percentage of good outcomes, assessed by the Rankin scale, was higher in earlier as well in delayed treatment and the fatality was lower compared to the comparison group. Conclusion: Mexidol increased the efficacy of treatment and may be recommended for treatment of patients with severe carotid IS.