The Foot and Ankle Ability Measure is a valid, reliable, and widely used self-reported questionnaire for the foot. It has been adapted and validated for a Turkish-speaking population. The purpose of this study was to provide evidence for validity and reliability of the Turkish version of the Foot and Ankle Measure (FAAM-T) in patients with chronic ankle instability (CAI). A total of 316 patients with CAI were enrolled. The internal consistency and test-retest reliability were evaluated. Validity was examined using correlations with the Short Form Health Survey version 2.0 (SF-36v2) questionnaire. Cronbach's alpha scores were 0.94 and 0.96 for the the FAAM-T ADL (Activities of Daily Living) and FAAM-T Sports subscales, respectively, indicating high internal consistency. For the second administration, Cronbach's alpha was found to be 0.96 for both subscales of the FAAM-T. The test-retest reliability of the FAAM-T was very high for both subscales with an intraclass correlation coefficient of 0.97 and 0.94, respectively (p < .001). The standard error of the mean and minimal detectable change were determined to be 2.5 and 6.7 for the FAAM-T ADL and 6.9 and 18.5 for the FAAM-T Sport. The FAAM-T ADL and Sport subscales were strongly correlated with the SF-36v2 PF (physical functioning; r = 0.51, r = 0.40, respectively; p = .001) and SF-36v2 PCS (physical component scale; r = 0.64, r = 0.55, respectively; p = .001). The weakest associations between the FAAM-T ADL and Sport and the SF-36v2 were noted for the mental health subscale (r = 0.08 and r = 0.03) and the SF-36v2 MCS (mental component scale; r = .05 and r = .006, respectively). This study provides evidence for validity, internal consistency, and test-retest reliability for the FAAM-T to evaluate patients with CAI. (C) 2018 by the American College of Foot and Ankle Surgeons. All rights reserved.