BACKGROUND: There is no study addressing transplantation of umbilical cord mesenchymal stem cells for the treatment of spinocerebellar ataxia.OBJECTIVE: To study the clinical effect of human umbilical cord stem cells transplantation in the treatment of autosomal dominant spinocerebellar ataxias. METHODS: Spinocerebellar ataxias patients selected from Stem Transplantation Center of the 455 Hospital of Chinese PLA were treated with umbilical cord mesenchymal stem cells transplantation via intrathecal injection. The number of umbilical cord mesenchymal stem cells was 107 per transplantation, once per week, for 4 weeks.RESULTS AND CONCLUSION: Both the total score of the International Cooperative Ataxia Rating Scale and Activities of Daily Living score were significantly decreased at 1 month after transplantation compared with before treatment (P < 0.05). The nerve function was significantly improved and the total effective rate was up to 16.7%. Experimental findings indicate that, transplantation of umbilical cord mesenchymal stem cells via intrathecal injection is a feasible and effective treatment to ameliorate the clinical efficacy of spinocerebellar ataxias patients and improve their quality of life.