BackgroundMotor control evaluation in subjects with functional ankle instability is questionable when both ankles of the same subject are compared (affected vs non-affected). ObjectiveTo compare the postural control and reaction time of ankle muscles among: basketball players with FAI (instability group), basketball players without FAI (non-instability group) and healthy non-basketball-playing participants (control group). DesignCase-control study. SettingLaboratory. ParticipantsInstability (n = 10), non-instability (n = 10), and control groups (n = 11). Main outcome measuresCentre of pressure variables (area, velocity and sway) were measured with a force platform. Reaction time of ankle muscles was measured via electromyography. ResultsA one-way ANOVA demonstrated that there were significant differences between the instability and non-instability groups in the fibularis longus (p < 0.001), fibularis brevis (p = 0.031) and tibialis anterior (p = 0.049) muscles. Repeated-measures ANOVA and post hoc analysis determined significant differences for the area between the instability and non-instability groups (p = 0.001). ConclusionBasketball players with FAI have reduced postural control and longer reaction time of the fibularis and tibialis anterior muscles.