We studied the results of treatment in 110 of 129 consecutive patients who had knee instability for which they underwent reconstruction of the knee ligaments at the Mayo Clinic. Thirty-one patients underwent different types of extraarticular reconstruction. Nine (29%) had recurrence of the knee giving way, and 11 (36%) had objective signs of instability on examination. Fifty-five patients underwent combined extraarticular and intraarticular reconstruction with either the Lam-Jones patellar tendon (PT) procedure (21 knees) or the Zarins-Rowe semitendinosus and iliotibial band (ST & ITB) procedure (34 knees). Only two knees (10%) with PT procedure and three knees (9%) with ST & ITB procedures continued to have giving way. Three patients in each group had recurrence of instability. Twenty-four knees with acute instability had either primary repair (17 knees) or primary reconstruction with ST & ITB procedures (7 knees). The results in these knees were superior to the results in the knees reconstructed for chronic instability. On the basis of our 2 year results, we believe that a combined intraarticular and extraarticular reconstruction is the procedure of choice in chronic knee instability and is a useful procedure in acute knee instability with irreparable tears of the anterior cruciate ligament.