Cladribine has a well-defined activity against lymphocytes, leading to their selective depletion.Objective: to determine the efficacy and safety of cladribine in the treatment of multiple sclerosis (MS) in real-world clinical practice.Material and methods. The study involved 82 patients (57 women and 25 men, mean age 36.4±9.3 years) with a disease duration of 2.2±1.5 years. Seven (9%) patients had secondary progressive MS (SPMS), 6 (7%) had rapidly progressive MS (RPMS) and 69 (84%) had highly active MS (HAMS). According to the instructions for use, oral therapy with cladribine was administered in two short courses (up to 10 days per year) to achieve a long-term effect on the immune system. The dose of cladribine was calculated based on the body weight.Results. The average frequency of exacerbations per year before starting therapy was 1.6, while it decreased to 0.2 during cladribine therapy. An exacerbation was observed in 18 patients (22%) at the end of the first course of cladribine treatment and in one patient (2.6%) after the second treatment course. Thus, the number of exacerbations decreased by 78% after the first year of treatment and by 97.4% after the second year of treatment. The mean EDSS score was 3.2±2.5 points before the start of treatment, 3.6±2.5 points after the first course of treatment and 3.4±2.5 points after the second course (p>0.05). MRI results showed a decrease in disease activity by 83% after the first course of cladribine therapy and by 97.4% after the second course. No serious adverse events occurred in any of the patients.Conclusion. We demonstrated efficacy and safety of cladribine in real-life clinical practice in MS patients with frequent exacerbations and rapid disability progression (SPMS, RPMS, HAMS).