A total of 175 patients were reviewed 1 to 8 years (average 42 months) after treatment of knee ligament injury in the acute stage. Two-thirds were treated operatively because of total ligament tears and the remainder, with minor injuries, were treated non-operatively. In two-thirds of the patients with total substance tear of the anterior cruciate early repair was successful. Repair of the posterior cruciate was generally successful. Functional loss was correlated to the presence of a pivot shift sign and with abduction or adduction instability in extension. An important reason for a poor result was either medial meniscectomy or some component of the injury being missed in the primary diagnosis. Diagnosis based on arthroscopic and clinical findings was more reliable when selecting patients for operative or non-operative treatment than was diagnosis based on clinical examination alone. There was no difference in the results of non-operative treatment between patients immobilized in plaster and those treated with early mobilization without weight-bearing.