Knee injuries are common in automobile pedestrian crashes. Lateral impact on the knee results in varus-valgus bending and causes injuries to collateral ligaments. Mechanical properties of ligaments under different loading conditions are important for developing human body finite element model to predict the injury risk to pedestrians in automobile crashes and for safer design of vehicle fronts. Tensile properties of the middle region of medial collateral ligament are reported between 0.0001/s to 140/s as obtained from isolated ligament tests. The results show a linear stress-strain response at lower strain rate whereas it is nonlinear and strain rate sensitive in dynamic loading conditions.