Abstract-Ankle ligament injury is the most common injury in athletic activities. This study examined balance problems in athletes with acute lateral ankle sprains. Thirty male athletes aged 20 to 35 years with right dominant side and traumatic ankle sprain were recruited through simple nonprobability sampling. We measured the sway index and limits of stability with the Biodex Balance System under different conditions. Functional balance was evaluated with two clinical tests: the Functional Reach Test and the Star-Excursion Balance Test. The results showed that balance ability in patients with acute lateral ankle sprain was significantly weaker under closed- versus open-eye conditions. Symmetry of weight-bearing on involved and sound limb in bilateral standing was not significantly different, but weight-bearing on the nondominant limb was significantly higher than on the dominant limb. We can conclude that balance problems occur after acute ankle sprains because of proprioception deficits and that the unconscious (reflexive) aspect of proprioception is more severely affected than the conscious (voluntary) aspect.