Purpose To test whether knee bracing restores normal rotational knee kinematics in anterior cruciate ligament (ACL)-reconstructed knees during high-demand, athletic activities. Methods Twenty male patients who had undergone unilateral ACL reconstruction with a bone-patellar tendon-bone autograft were assessed in vivo. The mean time from surgery to data collection was 26 months (range, 25 to 28 months). An 8-camera optoelectronic system was used to collect kinematic data while each patient performed 2 demanding tasks: (1) immediate pivoting after descending from a stair and (2) immediate pivoting after landing from a platform. Each task was performed under 3 conditions for the reconstructed knee: (1) wearing a prophylactic brace (braced condition), (2) wearing a patellofemoral brace (sleeved condition), and (3) without a brace (non-braced condition). As a control group, patients with intact ACLs were tested without any bracing. This study protocol was identical to the protocol of a previous study that investigated the effect of bracing on ACL-deficient athletes. Results For both tasks, the range of motion of tibial rotation was significantly lower in the intact knee compared with all 3 conditions of the ACL-reconstructed knee (P ���.014). Placing a brace or a sleeve on the ACL-reconstructed knee resulted in lower rotation than the non-braced condition (P ���.022), whereas no significant differences were found between the sleeved and the braced conditions (P ���.110). Conclusions Bracing limited the excessive tibial rotation in ACL-reconstructed knees during pivoting that occurs under high-demand activities. However, full restoration to normative values was not achieved. Thereby, braces have the potential to decrease rotational knee instability that still remains after ACL reconstruction. Level of Evidence Level II, prospective comparative study. �� 2013 by the Arthroscopy Association of North America.