BACKGROUND Extensive coronary dissections are rare but represent serious complications of percutaneous transluminal coronary angioplasty (PTCA). In order to prevent dissections in large coronary vessels (> or = 2.5 mm), we evaluated stent implantation without predilatation in 98 selected patients with favorable coronary anatomy and lesion morphology. METHODS Coronary stenting without predilatation was performed 41 times in the LAD, 41 times in the RCA, 11 times in the RCx, and 5 times in a vein graft. Mean diameter stenosis was 83 +/- 3%. Thirty-six patients had type A lesions and 62 patients type B lesions. Patients with type C lesions were excluded. Only premounted stents were used. RESULTS The clinical situation was stable angina in 68 patients, unstable angina in 18, and acute myocardial infarction in 12. Stenting without predilatation was successful in 92 patients (94%). In 6 cases (6%) it was not possible to cross the lesion with the premounted stent, and predilatation was necessary prior to successful stent implantation. Two out of 11 RCx-related lesions (18%) could not be stented without predilatation. However, ultimate success of PTCA was 100%. No stent was lost. Mean remaining stenosis amounted to 3 +/- 6%. Minor angiographically detectable dissections after stent deployment were noted in 8 patients (8%). Inflation time (30 +/- 22 s) and fluoroscopic time (4.5 +/- 2.1 min) compared favorably to standard procedures. During 30 d follow-up no subacute stent thrombosis, but 2 non-Q-wave myocardial infarctions due to lost side branches were reported. CONCLUSIONS Coronary stenting with premounted stents without predilation is feasible and safe in selected patients in order to reduce fluoroscopic and procedural time and to save costs. Furthermore, this procedure might reduce the risk of hazardous coronary dissections.