This study investigated the effect of the EndoButton CL (Smith & Nephew, Andover, MA) used for femoral graft fixation during anterior cruciate ligament reconstruction compared with an EndoButton with knot-fixed polyester tape on femoral and tibial bone tunnel widening and clinical outcome.A retrospective case-control study design was used. We compared 120 patients with EndoButton CL femoral fixation with 120 patients with an EndoButton with knot-fixed polyester tape. All patients had hamstring grafts and EndoButton femoral fixation and tibial fixation with a 7 x 30-mm metal interference screw. Tunnel widening was measured on anteroposterior (AP) and lateral radiographs at 12 months' follow-up. The largest tunnel width was measured for the femoral tunnel and in the tibial tunnel above the interference screw. Clinical outcome was assessed by objective and subjective International Knee Documentation Committee scores and KT-1000 (MEDmetric, San Diego, CA) knee laxity measurements.Femoral tunnel widening in the EndoButton group was 46.2% and 38.5% on the AP and lateral radiographs, respectively, and tibial tunnel widening was 24.9% and 33.2%, respectively. Femoral tunnel widening in the EndoButton CL group was 38.7% and 28.2% on the AP and lateral radiographs, respectively, and tibial tunnel widening was 10.9% and 23%, respectively. The EndoButton CL widening was lower for both femoral and tibial tunnels (P < .01). There were no differences between the groups for any of the clinical scores or KT-1000 knee laxity.This study showed that femoral anterior cruciate ligament graft fixation with an EndoButton and continuous polyester loop compared with an EndoButton with knot-fixed polyester tape reduced the radiographic tunnel widening at 1 year for both the femur and tibia. The reduction in tunnel widening was not associated with differences in clinical outcome with respect to International Knee Documentation Committee scores or KT-1000 knee laxity measurement.Level III, retrospective comparative study.