Athletes that have had anterior cruciate ligament (ACL) reconstruction are at a greater risk for reinjury. The relationship between ACL reconstruction and the dynamic postural sway index (DPSI) has not yet been examined. The purpose of this study was to examine the DPSI in a surgically reconstructed ACL limb compared to the uninjured leg in athletes that had been cleared for sport. It was hypothesized that in a bilateral limb comparison, the leg that underwent ACL reconstruction would demonstrate poorer postural stability measures (greater DPSI) during a single leg landing activity as compared to the non-surgical limb. Case-control study. 14 subjects (7 male, 7 female; age range 16-23 years) with a history of unilateral ACL reconstruction and clearance for return to sport (mean 14 months post-operatively, range 8 to 24 months) performed five single leg hops over a 12 inch hurdle in the anterior direction from a distance corresponding with 40% of their height, onto a force platform. DPSI for the medial-lateral, anterior-posterior, vertical directions and a composite score were calculated for each trial on the surgical and non-surgical legs. A multivariate analysis with repeated measures was used to compare surgical and non-surgical legs for the total DPSI measure as well as for each component. Significant differences (p < .05) in dynamic postural stability were observed in the medial-lateral, anterior-posterior, vertical indices and DPSI total between the surgical and non-surgical limb. Deficits in dynamic postural control persist in ACL-reconstructed limbs compared to the non-surgical limb after the clearance for full activity. Clinicians should consider assessing single limb dynamic stability prior to releasing the athlete back to full activity. Level 3.