AbstractBackground/AimThe Unified Multiple System Atrophy Rating Scale (UMSARS) has been broadly used to assess the progression of multiple system atrophy (MSA). In this study, we translated UMSARS into Japanese and tested the reliability and validity of the translated version for the assessment of Japanese patients with MSA.MethodUMSARS was translated into Japanese. For the evaluation of the reliability of the translated version, 60 and 70 participants with MSA were assessed by two neurologists using the Japanese versions of UMSARS‐I and UMSARS‐II, respectively. For the validation, 70 participants with MSA were evaluated by one neurologist using the Japanese versions of UMSARS‐I and UMSARS‐II, and other scales. Cronbach's alpha coefficient, Cohen's kappa coefficient [κ (w)], and Spearman rank correlation were calculated.ResultsCronbach's alpha coefficients of the Japanese versions of UMSARS‐I and UMSARS‐II were 0.87 and 0.90, respectively. The κ (w) values of UMSARS‐I and UMSARS‐II items were 0.61‐0.81 and 0.51‐0.86, respectively. The total UMSARS‐I score correlated well with the scores of Barthel Index, Schwab and England Activities of Daily Living Scale, Functional Independence Measure, and Movement Disorder Society‐Unified Parkinson's Disease Rating Scale (MDS‐UPDRS) part 2 (Spearman rank correlations, −0.75, −0.71, −0.82, and 0.81, respectively). The total UMSARS‐II score correlated well with the scores of International Cooperative Ataxia Rating Scale and MDS‐UPDRS part 3 (Spearman rank correlations, 0.85 and 0.86, respectively).ConclusionsThe Japanese version of UMSARS is reliable and valid for the assessment of the clinical severity of MSA in Japan.