We studied a group of anterior cruciate ligament-deficient athletes to identify whether joint position and direction of joint motion have a significant effect on proprioception. Twenty-nine anterior cruciate ligament-deficient athletes were tested for their threshold to detect passive motion at both 15 degrees and 45 degrees moving into the directions of both flexion and extension. The single-legged hop test was used to identify function in the deficient limb. Results demonstrated statistically significant deficits in threshold to detect passive motion for the deficient limb at 15 degrees moving into extension. For the deficient limb, threshold to detect passive motion was significantly more sensitive moving into extension than flexion at a starting angle of 15 degrees; at a starting angle of 15 degrees moving into extension threshold was significantly more sensitive than at a starting angle of 45 degrees moving into extension. We conclude that in deficient limbs proprioception is significantly more sensitive in the end ranges of knee extension (15 degrees) and is significantly more sensitive moving into the direction of extension. To effectively restore reflex stabilization of the lower limb we recommend a rehabilitation program emphasizing performance-based, weightbearing, closed kinetic chain exercise for the muscle groups that act on the knee joint.