The purpose of this study was to determine the effect of a softshell prophylactic ankle stabilizer (PAS) on performance in events involving speed, agility, and vertical jump during long-term use. The events examined were the 24.384-m sprint, 12.192-m shuttle ran, and vertical jump. Subjects were high school basketball players who were randomly assigned to either a PAS (n = 11) or a nonbraced control (n = 13) group. Results of the study revealed that the softshell PAS had no significant effect on any of the three performance events tested over a 3-month basketball season. However, there was a significant difference in 24.384-m sprint and 12.192-m shuttle run times across test sessions regardless of treatment group. In conclusion, the softshell PAS neither enhanced nor inhibited performance in activities involving speed, agility, or vertical jump during long-term use.