We have designed a scoring scale for knee ligament surgery follow-up emphasizing evaluation of symptoms of instability. Instability is defined as "giving way" during activity. Our scoring scale was compared to a slightly modified Larson scale in patients with anteromedial and/or anterolateral instability, posterolateral and straight posterior instability, chondromalacia patellae, and meniscus lesion. The two scales gave basically the same results in patients with meniscus rupture. In patients with unstable knees, the new scale gave a significantly lower total score. Thus, the new scale evaluates functional impairment due to clinical instability better than the modified Larson scale. The total score, with the new scoring scale, corresponded to the patients' own opinion of function and to the presence or absence of signs of instability.