Clinicians often are faced with the task of selecting an ankle orthosis that will provide protection against ankle sprain injury and will not have a deleterious effect on functional performance. The purpose of this study was to compare the effects of the DonJoy Ankle Ligament Protector (ALP) and the Aircast Sport-Stirrup (AS) on three functional performance tasks: the 40-m sprint run, the figure-of-eight run, and the standing vertical jump. Subjects were eight males and eight females who reported no history of ankle injury during the 6 months prior to testing; neurological condition; lower extremity surgery or pathology; or cardiac, pulmonary, vascular, or balance problems. Each subject performed all functional tasks on the first test day with both ankles unbraced and with one randomly selected ankle braced with one of the two orthoses. Each subject returned for testing on a second day and performed all tasks with both ankles unbranced and with the other orthosis on the previously selected ankle. Subjects also rated the orthoses for comfort and support. An ANOVA indicated that braced data were not significantly different than unbraced data and that data for the two orthoses did not differ significantly for any of the functional performance tasks. Seventy-five percent of the subjects reported the AS was more comfortable than the ALP, and 63% of the subjects indicated that the ALP provided more support than the AS. Neither orthosis had a deleterious effect on functional performance. The results may assist clinicians in selecting either of these orthoses for use in protection against ankle sprain injury.