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Background: Voice disorders can be found in many scenarios. Many people have experienced vocal problems in their lifetime. Such problems can occur occasionally or permanently during the course of life. Previous literature review showed that vocal fatigue usually occurs concurrently with voice disorders, though it could occur alone as well. Vocal fatigue is considered the first symptom of a vocal problem and usually improves after voice rest. Detecting vocal fatigue before an individual develops a voice disorder is extremely important. Objectives: This study aims to 1) translate the original VFI into the Thai version and 2) evaluate the psychometric properties of VFI-TH, including content validity, face validity, predictive validity (sensitivity and specificity), and reliability. Materials and methods: Participants in this study consisted of two groups comprising one group of 22 participants with voice disorders and another group of 60 participants with healthy voices. The age of participants was 18 years and older. Procedures: Cross-cultural protocol of translation was followed per Beaton, which consisted of five steps: Initial translation, synthesis of the translation, back translation, expert committee review, and pretesting. This study was divided into 2 phases. Phase I consisted of the first three steps of Beaton’s guideline, while Phase II was the evaluation of psychometric properties; content validity by expert committee review, face validity by data trial in ten participants with voice disorders, predictive validity through sensitivity and specificity by formula calculation, and reliability were examined by evaluating internal consistency through Cronbach’s Alpha co-efficiency. Results: The results showed that the VFI-TH had content validity, face validity, and predictive validity. For predictive validity, the percentages of sensitivity and specificity were 22.7 and 100, respectively, and internal consistency was 0.87-0.94, which meant very good or excellent. Conclusion: The VFI-TH had content validity, specificity, and reliability to detect vocal fatigue. However, the VFI-TH should be used along with other vocal assessments in adults aged 18 years and older.