Aim : To compare single-leg balance performance between subacute ankle sprain patients receiving no exercise therapy and healthy persons. Methods : Forty-eight subacute ankle sprain patients (age = 34.3 ±9.7 years) and 10 healthy persons (age = 30.1 ±4.7 years) participated in the study. Participants underwent an assessment of body functions and a 30-second single-leg balance test on a force plate under stable and unstable conditions. Center of pressure (COP) range, length and speed in mediolateral (ML) and anteroposterior (AP) directions were calculated. Results: All healthy persons finished the 30-second balance test under both conditions. Forty-three patients (90%; P=.374) were able to complete the test on the stable surface and 38 patients (79%; P=.125) on the unstable surface. Ankle sprain patients showed increased COP AP speed compared to healthy persons for stable conditions (P=.009) and a larger COP AP range for unstable conditions (P=.001). Furthermore, muscle strength in inversion and eversion were correlated to COP performance (P<.050). Conclusion : Specific ankle strength exercises, including muscle strength exercises in the frontal plane, might improve balance performance in ankle sprain patients.