There are numerous rehabilitation protocols for patellofemoral problems, but there is little objective data to determine the most effective exercise program to conservatively treat this disorder. The purpose of this study was to determine the effect of open and closed chain exercise and knee joint position on patellar tracking in lateral patellar compression syndrome. Computed tomography scans of the patellofemoral joint were performed with the leg in three muscle conditions and at five knee angles in 16 subjects with lateral patellar compression syndrome. Patellar tracking was evaluated by measuring congruence angle. Relaxed and closed chain conditions demonstrated improved congruence as compared with the open chain condition at 0, 10, and 20 degrees of knee flexion (p < .0001). Open chain strengthening techniques appear to be most appropriate after 30 degrees of knee flexion. The three muscle conditions demonstrated progressively improved patellar congruence from 0 to 40 degrees of knee flexion.