The aim of this study was to investigate effects of bone impaction technique on tunnel enlargement after ACL reconstruction at a minimum 2 years follow-up. Two groups of patients who had been operated upon with the same arthroscopic technique with the exception of tibial tunnel constitution were compared. Twenty-one patients of group A (drilling to 6 mm followed enlargement to 8-9 mm by using dilators) and 23 patients of group B (directly drilling to the size of the graft) were evaluated clinically and radiographically based on multislice computerised tomography (MSCT) retrospectively. At follow-up, there was no statistical difference between tunnel diameters between two groups at the femoral site, but significant difference at the tibial site (p = 0.00192 for coronal; p = 0.0171 for sagittal diameter). Both groups were comparable according pre- and postoperative Lysholm and IKDC scores (p < 0.5 Mann-Whitney U test). Compacted tunnel walls may resist enlargement, suggesting this technique resulted in better tunnel diameter values especially with intratunnel fixation.