We prospectively determined the effectiveness of an immediate knee motion and early intervention program to prevent permanent motion limitations in a consecutive series of patients who had anterior cruciate ligament autogenous patellar tendon reconstruction for isolated rupture (219 knees) or combined with other procedures (224 knees). The subjects were placed into either a progressive or delayed rehabilitation program and were followed for at least 12 months postoperatively. At follow-up a normal range of motion (0 degrees to at least 135 degrees) was found in 436 knees (98%), and mild losses of extension (-5 degrees) were found in 7 knees. Twenty-three knees (5%) required interventions; 9 had extension casts, 9 had gentle manipulations under anesthesia, 3 had arthroscopic debridements, and 2 had continuous epidural anesthetic and inpatient therapy. All of these 23 knees regained full motion. The 7 patients with mild losses of extension had refused treatment intervention. The 0% incidence rate of permanent arthrofibrosis, and 0.7% reoperation rate for knee motion limitations, demonstrated the effectiveness of our program.