Eighty-six chronic anterior cruciate ligament (ACL)-injured patients were quantitatively measured for anterior knee stability preoperatively and at 2 years or later (mean, 30 months) postoperatively to examine the influence of preoperative knee laxity on the postoperative knee stability restored by the ACL reconstruction using multiplied hamstring tendon graft. The patients were divided into 3 groups according to the preoperative injured minus normal anterior laxity difference (AL-D) (group I [n = 27] <5 mm, group II [n = 48] 5 to 9 mm, group III [n = 11] >10 mm). The 3 groups were comparable in gender, age, meniscal status, graft excursion measured during operation, time from injury to operation, acid activity level. The postoperative AL-D in group I was 0.8 +/- 1.7 mm, that in group II was 1.1 +/- 1.6 mm, and in group III was 1.5 +/- 1.4 mm. There were no significant statistical differences among these 3 groups. With our surgical technique including postoperative rehabilitation, patients with severe instability could be treated successfully without needing any additional procedures such as extra-articular augmentation or specially designed postoperative rehabilitation programs.