A series of prospective studies have been performed using allograft tissue for anterior cruciate ligament (ACL) reconstruction. This type of procedure has been shown to effectively control joint displacement and increase overall patient function in a specific patient population. In considering the use of allograft tissue, the surgeon must take into account the indications and contraindications as well as graft preparation and possible immune response. The current clinical trend is utilization of allograft tissue for patients who have previously failed autograft surgery, have patellofemoral arthrosis, or have a long-standing chronic ACL deficiency. The rehabilitation process for these types of patients is very similar to our approach in the autograft patient. It is important for the clinician to facilitate an early motion program after surgery, early exercise protocols, and early weight bearing. However, as in any protocol, careful evaluation is critical. Three different studies reported by our group have shown the allograft to be successful in controlling joint displacement. On testing with the KT-1000 arthrometer, 69 percent of acute repairs had less than 3 mm of anterior posterior displacement; 26 percent of these patients had only 3-5 mm of anterior displacement compared to the contralateral knee. A second study of chronic anterior cruciate ligament patients showed 54 percent had under 2.5 mm of anterior displacement and 34 percent had 3-5 mm of anterior displacement when compared to the contralateral knee. With effective implementation of a rehabilitation program, only 5 percent of our acute and chronic patients developed a motion complication, and only 9 percent had patellofemoral complaints. Using a strict rating system, the overall rating of these patients showed that 89 percent were in the excellent to good range, which allowed them to once again participate in recreational or competitive sports. Only 11 percent had a fair to poor result; 50 percent of that group chose not to return to sporting activity for nonknee related causes. These studies have shown that allograft ligament reconstructive techniques are effective and improve functional ability in the chronic anterior cruciate ligament patient. Use of these tissues should, however, be on a selective basis. Caution must be used by the physician when using these tissues, and the physical therapist must recognize that the protocol for postoperative management is essentially the same as for the autograft techniques. J Orthop Sports Phys Ther 1992;15(6):294-302.