The prudence of prophylactic ankle taping continues to be questioned as recent studies have identified other forms of ankle stabilization as more effective means of injury prevention. The purpose of our study was to compare the effectiveness of three ankle prophylaxes (adhesive taping, lace-up brace, and semirigid orthosis) with a control condition (no support) in limiting inversion under dynamic loads imposed by repetitive walking (4 mph) and running (9 mph) on an 8.5 degrees laterally tilted treadmill. Ten subjects participated in four separate testing sessions in which they were videotaped while walking and running on a tilted treadmill before and after 20 minutes of vigorous exercise. Average maximum inversion angle was determined through biomechanical analysis of rearfoot motion for each experimental condition and analyzed with repeated measures ANOVA and Scheffé post hoc tests. There were significant differences in the average maximum inversion angle between the ankle devices at 4 and 9 mph, and between pre-exercise and postexercise measurements at 4 mph, between the semirigid orthosis and the control condition at 4 and 9 mph, and between the lace-up brace and the control condition at 4 mph. Overall, the semirigid orthosis provided the most inversion restraint during dynamic loading, followed by the lace-up brace, tape, and control condition. We concluded that the lace-up brace and semirigid orthosis evaluated were very similar in restricting inversion, and that both devices limited postexercise inversion significantly more than ankle taping.