This research was funded in part by a grant from the Ferrante and Jackson Physical Therapy Research Fund. Recent criticism in the literature regarding the effectiveness and costs of ankle taping has lead to an increased use of commercial ankle braces. This study compared the effectiveness of four commercially available ankle braces in limiting range of motion at the ankle before and after a brief exercise session. Twenty-seven healthy subjects, ages 18-36, were tested across all four bracing conditions. For each brace application, a combined passive inversion-eversion movement was evaluated three times: 1) prebrace application, 2) immediate postbrace application, and 3) following a 10 min exercise session. Subjective ratings of brace comfort, support, and preference were also documented. All four braces significantly limited more motion compared to the unbraced ankle, both before and after exercise (p </= 0.05). Additionally, the Aircast(R) Sport-Stirrup and Ankle Ligament Protector significantly limited more ankle motion than the Swede-O Ankle Support(R) and Kallassy Ankle Support(R), both before and after exercise (p </= 0.05). Subjectively, the Sport-Stirrup was perceived as the brace providing the most support, but the Kallassy was the most comfortable and most preferred of the four braces studied. These findings demonstrate that provided support must be balanced with perceived comfort in the prescription of an ankle orthosis. J Orthop Sports Phys Ther 1992;15(1):10-18.