A performance test simulating components of sports was devised to evaluate dysfunction after ACL injury. The test included a one-leg hop, running in a figure of eight (straight running and turn running measured separately), running up and down a spiral staircase, and running up and down a slope. Twenty-six men with ACL injury, most of them soccer players, and 66 uninjured male soccer players were studied. Patients with ACL injury performed significantly less well than the uninjured players. Test items of special interest were turn running in the figure of eight, stair running, and slope running, all of which place high demand on the knee. It is concluded that a performance test of this design is useful for monitoring rehabilitation and for evaluating the patient's condition. Before sports can be resumed at the original level, normal strength and normal performance should be regained.