Background <p>Patient-Reported Outcome Measure (PROMs) are essential instruments for assessing outcomes in clinical trials, as they represent, in a standardized way, the direct report of patients about their own experiences with the disease. To better understand the health and well-being of the population with ataxia, the Patient-Reported Outcome Measure of Ataxia (PROM-Ataxia) was developed in English.</p> Aim <p>to translate the PROM-Ataxia to Portuguese and culturally adapt it for use in Brazil.</p> Methods <p>We followed the ISPOR TCA Task Force guidelines. Researchers from two geographically and culturally distant ataxia care centers, located 4,200&#xa0;km apart, produced two initial versions in Portuguese. The reconciled version was back translated, improved by the opinion of other specialists in ataxia in the country, and sent to the original author, who approved the preliminary Brazilian version. This version was then taken to cognitive debriefing with ataxic patients followed at one of the two participant sites - Porto Alegre and Fortaleza.</p> Results <p>Fourteen Brazilian patients participated in the debriefing. They found PROM-ataxia to be adequate and to cover all the significant impacts of ataxia on their lives. Some items were considered ambiguous. Semantic and conceptual issues were identified and resolved with minor translation changes that improved the cross-cultural adaptation of the questionnaire.</p> Conclusion <p>The Brazilian version of PROM-ataxia is now complete. Further psychometric studies are needed to validate its efficacy as an outcome measure, particularly in clinical trials.</p> Clinical Trial Number <p>Not applicable</p>