Objective: To investigate the effects of different rearfoot orthotics on postural sway during unilateral stance after lateral ankle sprain. Design: Repeated-measures 3-factor analysis of variance on postural sway length and velocity in the frontal and sagittal planes with factors being stance leg(injured, uninjured), session (within 3d, 2wk, 4wk postinjury), and condition (6 orthotic conditions). Setting: University biomechanics laboratory. Patients: Fifteen collegiate athletes with acute, unilateral first- or second-degree lateral ankle sprain. Interventions: Balance testing was performed under 6 conditions: (1) shoe only, (2) molded Aquaplast orthotic, (3) lateral heel wedge, (4) 7 degrees medially posted orthotic, (5) 4 degrees laterally posted orthotic, and (6) neutral orthotic. Main Outcome Measures: Postural sway length and postural sway velocity in the frontal and sagittal planes. Results: Significant main effects were found for side and session, but not orthotic condition, for all 4 dependent variables. Postural sway length and velocity were greater on the injured limbs as compared with the uninjured limbs during the first 2 sessions but not during the third session. None of the orthotics significantly reduced postural sway compared with the shoe-only condition after lateral ankle sprain. Conclusions: Rearfoot orthotics, irrespective of design pr posting, were ineffective at improving postural sway after lateral ankle sprain.