This observational single-center trial examines the safety and efficacy of unplanned endoluminal stenting for the treatment of a suboptimal angiographic result (defined as a residual stenosis after angioplasty of 40% to 50% without delayed runoff as estimated by visual assessment) after conventional coronary angioplasty in native, new-onset, coronary artery stenoses. Between October 1991 and April 1994, 101 patients with suboptimal results after coronary angioplasty in new-onset lesions were treated by endoluminal Wiktor (41 patients) and Palmaz-Schatz (60 patients) stent implantation. Stenting was a technical and angiographic success in all cases. In-hospital complications were subacute closure (2%) and vascular complications at puncture site necessitating surgery (12%) or blood transfusion (3%). No myocardial infarction occurred, nor was any urgent bypass surgery performed. At follow-up restenosis was detected in 16 (20%, 80% angiographic follow-up rate) patients requiring repeat angioplasty (8%) and elective bypass grafting (4%). Myocardial infarction was not documented. However, one patient died suddenly at 5 months of follow-up. The unplanned use of intracoronary stents is a safe and effective therapeutic option for the treatment of a suboptimal angiographic result after conventional angioplasty in new-onset lesions. This approach guarantees a high immediate angiographic success but implies a considerable incidence of vascular complications at puncture site.