The structural properties of the four major human kneeligaments were investigated at different loading rates.Bone-ligament-bone specimens of the medial and lateralcollateral ligaments and the anterior and posteriorcruciate ligaments, obtained from post-mortem humandonors, were tested in knee distraction loading indisplacement control. All ligaments were tested in theanatomical position corresponding to a fully extendedknee. The rate dependence of the structural response ofthe knee ligaments was investigated by applying loadingunloadingcycles at a range of distraction rates. Rampsto failure were applied at knee distraction rates of 0.016mm/s, 1.6 mm/s, or 1,600 mm/s. Averages and corridorswere constructed for the force response and the failurepoint of the different ligaments and loading rates. Thestructural response of the knee ligaments was found todepend on the deformation rate, being both stiffer andmore linear at high loading rates. This rate dependence was found to be more pronounced at high loading rates.