Material and Method: A Thai version of the International Prostate Symptom Score (IPSS-Th) was developed after conducting many steps. The original English version of the International Prostate Symptom Score (IPSS) was translated into Thai by three urologists working independently. After having compared the original English version with various translations, the final Thai version was obtained. Fifty Thai males possessing a good understanding of both English and Thai were asked to complete the Thai version of the IPSS. Two weeks later, they were asked to complete the English version of the IPSS. Internal consistency was assessed using Cronbach’s alpha. Next, 118 Thai males were tested using the Thai version of the IPSS and retested after two weeks. As such, the reliability of the Thai version of the IPSS was evaluated using the test-retest method.

Results: For the Thai IPSS version, Cronbach’s alpha was 0.77 and the English version of the IPSS was 0.88. The test-retest reliability was 0.96.

Conclusion: The Thai version of the IPSS was found to be reliable and should be a useful tool for patient assessment, follow-up, and research in the population of Thai-speaking patients.

Keywords: IPSS, Thai version, Prostate symptom score