OBJECTIVE: To determine whether subjects with functional ankle instability suffered kinesthetic deficits in the injured ankle compared with the healthy ankle and to examine the effect of prophylactic ankle bracing on kinesthesia in uninjured and functionally unstable ankles. DESIGN AND SETTING: We tested subjects over 4 consecutive days in a climate-controlled athletic training/sports medicine laboratory setting. A single-group time-series design enabled all subjects to serve as their own controls. A different bracing condition was tested on each of those occasions. SUBJECTS: Sixteen subjects (8 men, 8 women; age = 21.6 +/- 1.7 years; mass = 73.5 +/- 15.0 kg; height = 172.9 +/- 8.8 cm) with unilateral functional ankle instability participated in this study. MEASUREMENTS: Kinesthetic threshold-to-detection of passive motion (TTDPM) measurements were obtained during passive inversion and eversion movements (0.5 degrees.s(-1)) under 4 different bracing or taping conditions (unbraced, Swede-O Ankle Lok, Aircast Air-Stirrup, and tape). RESULTS: We analyzed the data using a 3-factor analysis of variance with repeated measures on the ankle and motion factors. Threshold-to-detection of passive motion scores in the unbraced condition were significantly better than the TTDPM scores in any of the other 3 test conditions. No significant differences were seen in TTDPM scores between the 2 ankles under any of the 4 conditions. CONCLUSIONS: Threshold-to-detection of passive motion scores did not differ in uninjured ankles and those with functional instability; however, bracing with either the Ankle Lok or Air-Stirrup decreased the ability to detect passive motion when compared with the no-tape (unbraced) condition. Further research is needed to determine the exact contributions of taping and bracing on ankle joint kinesthesia.