In this study, 24 consecutive patients with symptomatic chronic anterior cruciate ligament ruptures who had ligament reconstructions with the Leeds-Keio artificial ligament were observed for a minimum of 2 years or until ligament failure, whichever came first. The evaluation included a clinical examination, Lysholm knee score, and testing with a KT-1000 arthrometer. Within 2 years after surgery three patients underwent reoperation because of a rupture of the artificial ligament leading to instability. Another six patients developed significant subjective instability, even during ordinary activity. Only eight patients had a subjectively stable knee. Eleven patients scored 84 points or less on the Lysholm knee score, and 13 patients scored 85 points or more. The mean difference in anterior translation between the reconstructed knee and the opposite knee tested with the KT-1000 arthrometer was 3.7 mm. The high incidence of unstable knees, 9 of 24, due to insufficiency of the artificial ligament in this 2-year follow-up study strongly suggests that the Leeds-Keio artificial ligament is not an effective device for the reconstruction of the anterior cruciate ligament.