Results from earlier trials performed before the implementation of optimal stent deployment techniques suggest that stenting for restenotic lesions may be associated with a higher risk of restenosis when compared with de novo lesions. The aim of this study was to compare the short- and long-term outcome of optimal stent deployment in restenotic versus de novo lesions. In all, 1,865 consecutive patients with 2,707 de novo lesions and 489 patients with 633 restenotic lesions underwent intravascular ultrasound-guided optimal stent deployment. In-hospital outcome was similar for both groups, except for a higher incidence of non-Q-wave myocardial infarction in the de novo group (14.6% vs 8.6%, p = 0.001). At 12-month follow-up, there was no statistical significant difference in the incidence of death or myocardial infarction, but event-free survival was better in the de novo lesion group of patients (74.5% vs 63.7%, p = 0.001). There was a higher incidence of target lesion revascularization in the restenosis group (25.1% vs 13.0%, p = 0.001). By multivariate analysis, restenotic lesions, vein graft lesions, and diabetes mellitus were strong determinants of repeat revascularization, whereas larger preprocedural reference vessel minimal lumen diameter and larger final minimal lumen diameter were associated with a reduced chance of restenosis and increased event-free survival. This study shows that optimal stent deployment for restenotic and de novo lesions has favorable short- and long-term outcome. However, the incidence of target lesion revascularization was significantly greater in restenotic lesions. Saphenous vein graft lesions and diabetes mellitus were confirmed as other independent risk factors for clinical restenosis. Copyright (C) 2000 Excerpta Medica Inc.