The Fatigue Severity Scale (FSS) is one of the most frequently used self-rating scales for fatigue in Parkinson's disease (PD) and it lacks a validated Brazilian-Portuguese version. OBJECTIVE: To determine the construct validity and reproducibility of a Brazilian-Portuguese version of the FSS in patients with PD. METHODS: In a cross-sectional study, a Portuguese-language version of the FSS was applied to 30 patients with PD (62±11 years-old). The Parkinson's disease questionnaire (PDQ-39) was used as the validation criterion, while the Hoehn and Yahr scale, the Unified Parkinson's Disease Rating Scale (UPDRS), and the Beck Depression Inventory were employed to analyze the correlations with the FSS score. RESULTS: The test-retest intraclass correlation coefficient was 0.91 (p<0.01) for the Brazilian-Portuguese version of the FSS score, which was highly correlated with the PDQ-39 overall score (r=0.93; p<0.01) and the Beck Depression Inventory (r=0.75; p<0.01). It showed a correlation with the Hoehn and Yahr scale (r=0.40; p=0.02), and with the UPDRS as well (r=0.45, p=0.01). CONCLUSIONS: The Brazilian-Portuguese version of the FSS is valid and reproducible for using in Brazilian patients with PD.