The purpose of this study was to evaluate the clinical results of arthroscopic treatment of nonunited anterior cruciate ligament (ACL) tibial avulsion fracture with a figure-of-8 suture fixation technique. Nineteen cases of nonunited ACL tibial avulsion fracture were treated with an arthroscopic figure-of-8 suture fixation technique. The patients were followed up and evaluated according to the International Knee Documentation Committee, Lysholm, and Tegner rating scales. The time interval between the previous injury and this operation was 1 to 8 years, with a mean of 3.6 years. Eighteen patients were followed up for more than 2 years (range, 24 to 30 months; mean, 26 months). The fracture was united within 3 months after surgery in all cases. At the latest follow-up, there was neither extension nor flexion limitation in all patients. With the exception of 1 patient who had a 1 degrees positive Lachman test with a firm end-point, all of the patients had a negative Lachman test. The side-to-side difference in knee anterior laxity was 0 to 2 mm in 17 patients and 4 mm in 1 patient. The Lysholm score was 91 to 100, with a mean of 96.7 +/- 1.9 (compared with 74.3 +/- 4.6 before surgery, P < .05). Fifteen patients returned to their former activity level. The Tegner scores before injury, preoperatively, and at latest follow-up were 6.1 +/- 0.6, 3.6 +/- 1.0, and 6.0 +/- 0.8, respectively; there was no statistically significant difference between the preinjury and postoperative Tegner scores (P > .05). According to the International Knee Documentation Committee scale, 17 patients' knees were graded as normal and 1 patient's knee was nearly normal. Arthroscopic treatment of nonunited ACL tibial avulsion fracture with a figure-of-8 suture fixation technique can ensure fracture healing and restore the stability and function of the joint in most patients. Level IV, therapeutic case series.