Introduction. In 2018–2020, a study was conducted in the Russian Federation on the efficacy and safety of highdose immunosuppressive therapy with autologous hematopoietic stem cell transplantation (HDIT-AHSCT) in multiple sclerosis (MS).The aim of the study was to analyze preliminary data on the effectiveness and safety of the HDIT-AHSCT in patients with MS who participated in the clinical approbation of the method.Material and methods. 21 patients were included in a single-center Pavlov University (Saint Petersburg) observational study. In 10 patients (47.6%) the Expanded Disability Status Scale (EDSS) ranged from 1.0 to 4.0, in 10 — from 4.5 to 6.0 points, 1 patient with primary-progressive MS (PPMS) had 6.5 EDSS points. Cyclophosphamide conditioning regimen (200 mg/kg) in combination with rituximab (1000 mg/m2) was used. Neurological assessment (EDSS, SNRS, T25-FW, 9-HPT, PASAT, MoCA, HADS) and brain MRI were performed before and after 12 months. The early and long-term complications of HDIT-AHSCT were also analyzed.Results. One year after HDIT-AHSCT improvement and significant improvement were noted in 10 patients (47.6%), stabilization — in 8 (38.1%), relapse/progression — in 3 (14.3%). A lower effect was observed in patients with spasticity of more than 3 points by the MAS. According to MRI data 18 patients (85.7%) had stabilization of MS with no disease activity after 1 year, that met the No Evidence of Disease Activity (NEDA) criteria. Long-term complications included autoimmune thyroiditis (n = 1) and amenorrhea in two patients older than 38 years. No TRM were registered during the observation period.Conclusion. HDIT-AHSCT is an effective method of treating patients with multiple sclerosis. The results of the research demonstrate the safety and effectiveness of HDIT-AHSCT and it can be used to expanse the opportunities for providing treatment of patients with MS in the Russian Federation.