To determine the role that an increased caudal slope of the tibia might have on the incidence of anterior cruciate ligament (ACL) injury, tibial slope was measured in 49 patients (50 knees), with noncontact ACL injury mechanisms (group 1) and an age-matched group of 39 patients (50 knees) with a diagnosis of patellofemoral pain syndrome (group 2). No significant difference was noted in mean posterior slope between the two groups (group 1: 9.7+/-1.8 degrees and group II: 9.9+/-2.1 degrees) or after controlling for bilateral patients in two separate trials. These results indicate that increased caudal tibial slope does not appear to be a risk factor in the creation of noncontact injuries to the ACL.