In recent studies, the technique of high pressure balloon dilation for stent optimization has been shown to improve procedural success and to reduce subacute closure after stenting. The late clinical outcome, however, is still uncertain after stenting with high pressure balloon dilation. Therefore, we evaluated the effect of high pressure balloon dilation on the subsequent clinical course in patients after intracoronary stenting. One-hundred ninety patients with 197 lesions were treated with Palmaz-Schatz stent implantation. Intracoronary stenting without high pressure balloon dilation and with anticoagulation was performed in 55 patients with 55 lesions (phase 1), whereas intracoronary stenting with high pressure balloon dilation, without anticoagulation was done in 135 patients with 142 lesions (phase 2). We compared the angiographic and clinical results immediately and at follow-up in both phase 1 and phase 2. Coronary angiography was repeated at 6 months in 147 patients (79%) and 150 lesions (77%). The overall incidence of angiographic restenosis was 24% (31% in phase 1 and 21% in phase 2). Angiographic restenosis occurred in 18% of elective stenting on de novo lesions (23% in phase 1 and 15% in phase 2). The target lesion revascularization rate was 19% (26% in phase 1 and 16% in phase 2). The restenosis rate was significantly reduced with high pressure balloon dilation in the infarct-related artery and for a stent size of ³ 4.0 mm (p < 0.05). In conclusion, intracoronary stenting using high pressure balloon dilation technique without anticoagulation has good immediate results, negligible stent thrombosis and may have a tendency towards lower rates of restenosis.