Objectives: To evaluate the effects of an anterior ankle-foot orthosis (AFO) on static and dynamic postural stability in hemiplegic patients.Design: A cross sectional assessment of hemiplegic subjects with and without an AFO.Setting: Outpatient department of a rehabilitation hospital.Patients: A convenience sample of 24 subjects who had been prescribed an anterior AFO.Outcome Measures: Postural sway index and postural symmetry (body weight distribution through the affected leg) when standing were measured as static postural stability. Maximal balance range in anterior-posterior and lateral directions and the affected leg's weight bearing after weight shift to affected side were measured as dynamic postural stability.Results: When wearing the anterior AFO, there was no significant difference and small effect size (r < 0.3) in postural sway index (p = .35), postural symmetry (p = .21), and maximal balance range in anterior-posterior direction (p = .46). There was a significant improvement and large effect size (r > 0.5) in lateral weight shifting (p < .01) and weight bearing through the affected leg after weight shifted to the affected side (p < .01).Conclusions: The significant effects of the anterior AFO in long-term hemiplegic patients were on lateral weight shifting and weight bearing through affected leg after weight shifted to the affected side. Postural sway, postural symmetry, and anterior-posterior weight shifting were not significantly affected.