Objective. To assess the relationship between foot alignment and transverse plane knee motion during a single leg-landing task.Design. Clinical trial.Setting. Hospital biomechanics laboratory.Participants. Seven healthy young women without excessive forefoot, arch, or rear-foot malalignments.Methods and measures. Varus and valgus foot malalignments were mimicked by placing 8 o medial and lateral posted orthotics into the shoes before participants performed three landings from a drop jump off a 43cm high platform. The change in tibiofemoral rotation relative to the no orthotic condition was measured.Results. The medial posted orthotic resulted in 3.1+/-5.5 o less internal tibiofemoral rotation as compared to the nonorthotic condition, while the lateral posting produced 2.6+/-2.2 o more internal tibiofemoral rotation (t 6 =-2.51, p=<0.03).Conclusions. Orthotic induced malalignments altered the magnitude of tibiofemoral rotation during a closed kinematic chain activity. Orthotic posting may be used to reduce the rotary stress on the knee during landing activities.