We conducted a prospective, randomized study of open and closed kinetic chain exercises during accelerated rehabilitation after anterior cruciate ligament reconstruction to determine if closed kinetic chain exercises are safe and if they offer any advantages over conventional rehabilitation. The closed kinetic chain group used a length of elastic tubing, the Sport Cord, to perform weightbearing exercises and the open kinetic chain group used conventional physical therapy equipment. Results are reported with a minimum 1-year followup (mean, 19 months). Pre- and postoperative evaluation included the Lysholm knee function scoring scale, Tegner activity rating scale and KT-1000 arthrometer measurements. Overall, stability was restored in over 90% of the knees. Preoperative patellofemoral pain was reduced significantly; 95% of the patients had a full range of motion. The closed kinetic chain group had lower mean KT-1000 arthrometer side-to-side differences, less patellofemoral pain, was generally more satisfied with the end result, and more often thought they returned to normal daily activities and sports sooner than expected. We concluded that closed kinetic chain exercises are safe and effective and offer some important advantages over open kinetic chain exercises. As a result of this study, we now use the closed kinetic chain protocol exclusively after anterior cruciate ligament reconstruction.