To identify athletes at a higher risk of anterior cruciate ligament (ACL) injury, we developed a video-based screening test focused on hip abductor and rearfoot function. However, age differences in hip or reafoot motion as a contributor to dynamic knee valgus remains unclear. The purpose of this study was to determine how age differences contribute to hip or reafoot motions. Eighty-three female basketball players (41 junior high-school and 42 high-school students) agreed to participate in this study. Participants were measured for hip rotation angle, tibial rotation angle, ankle dorsi-flexion angle, navicular drop and general joint laxity. Subjects also performed single-legged squatting and drop landing from a 30 cm box. Knee-in distance (KID) and Hip-out distance (HOD) were measured using 2-dimensional video images filmed at 30 Hz. Additionally, Dynamic Trendelenburg Test (DTT) and Heel-Floor Test (HFT) were performed. The prevalence of HFT-positive in junior high-school and high-school athletes were not statistically different. DTT-positive during landing was more prevalent in junior high-school athletes than in high-school athletes (P<0.05). Junior high-school athletes demonstrated greater HOD values in squatting than high-school athletes (P<0.05). The range of motion in high-school athletes was significantly greater than in junior high-school athletes in tibial external rotation, hip internal and external rotation (p<0.01). The navicular drop in junior high-school athletes was significantly greater than in high-school athletes (p<0.01), however the navicular height was greater in high-school athletes (p<0.01). Player's age is an important consideration in ACL injury preventative conditioning.