OBJECTIVE To explore the clinical characteristic of the multiple-ligament injured knee and evaluate the protocol, technique and outcome of treatment for the multiple-ligament injured knee. METHODS From October 2001 to March 2005, 9 knees with combined anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) tears in 9 patients were identified with clinical and arthroscopic examinations. Of them, 5 knees were combined with ruptures of posteromedial corner (PMC) and medial collateral ligament (MCL), 4 with disruptions of posterolateral corner (PLC), 2 with popliteal vascular injuries and 1 with peroneal nerve injuries. Six patients were hospitalized in acute phase of trauma, 2 received repairs of popliteal artery and 4 had repairs of PMC and MCL. Reconstructions of ACL and PCL with autografts under arthroscope were performed in all patients at 4 to 10 weeks after trauma, including reconstruction of PLC with the posterior half of biceps femoris tendon tenodesis in 4 patients and reconstructions of PMC and MCL with femoral fascia in 1 patient. RESULTS No severe complications occurred at early stage after operation in the 9 patients. All of them were followed-up for 10-39 months with an average of 23.00 months+/-9.46 months. Lysholm score was 70-95 with an average of 85.00+/-8.29. International Knee Documentation Committee (IKDC) score was from severely abnormal (Grade D) in 9 knees at initial examination to normal (Grade A) in 2 knees, nearly normal (Grade B) in 6 knees and abnormal in 1 knee at the last follow-up. Of the 9 patients, 7 returned to the same activity level before injury and 2 were under the level. CONCLUSIONS The multiple-ligament injured knee with severe instability is usually combined with other important structure damages. Therefore, careful assessment and treatment of the combined injuries are essential. Reconstructions of ACL and PCL under arthroscope, combined with repairs or reconstructions of the extraarticular ligaments simultaneously or in stages, have advantage of minimal trauma in surgery and satisfactory outcome.