Aggressive balloon dilatation is currently performed to assure full stent expansion and minimize the risk of stent thrombosis. It is not known if aggressive stent expansion leads to further increases in intimal proliferation and restenosis. A retrospective analysis was performed of 688 consecutive coronary narrowings in which stents were implanted. Angiographic follow-up was performed and quantitative coronary angiographic measurements were obtained using electronic calipers. Patients were divided into 2 groups. Group A (212 narrowings) had stents implanted before 1993, before the routine use of aggressive stent expansion techniques. Group B (476 narrowings) had stents implanted after 1993, when oversized balloons or high-pressure inflations were performed inside stents. Comparisons were made between angiographic changes and clinical outcomes between the 2 groups. Group B lesions had less favorable characteristics due to longer lengths of lesions. Despite this there was less angiographic and clinical restenosis in this cohort. There was no difference in late loss between the 2 groups. Thus, aggressive stent implantation techniques were not associated with increased late loss or restenosis.