The Functional index of hand osteoarthritis (FIHOA) is a commonly used patient-reported outcome questionnaire designed to measure function in patients with hand osteoarthritis. The objective of this study was to evaluate the validity and reliability of the Persian version of the FIHOA. The Persian-translated version of FIHOA was administered to 72 native Persian-speaking patients in Iran with hand osteoarthritis. Thirty-six of the patients completed the questionnaire on two occasions 1 week apart. The physical component of the SF-36 and a numerical rating scale were used to evaluate the construct validity of the Persian version of FIHOA. Internal consistency was high (Cronbach's alpha = 0.89). Test-retest reliability for the total score was excellent (weighted kappa = 0.89, 95% CI 0.79-0.94). A significant positive correlation between total FIHOA score and numerical rating scale (r = 0.70) and a significant negative correlation between total FIHOA score and the physical component scale of the SF-36 (r = -0.76) were observed. The Persian version of the FIHOA showed adequate validity and reliability to evaluate functional disability in Persian-speaking patients with hand osteoarthritis.