This is the first prospective study investigating the safety and efficacy of the new Coroflex Coronary Stent System regarding the incidence of major adverse cardiac events and the angiographic results during 6-month follow-up. The balloon-expandable Coroflex Stent is composed of stainless steel 316L, designed as a "slotted tube" with a 0.04" (0.97 mm) low crossing profile and high flexibility. A metal coverage of 12% allows easy side branch access. Between September 1998 and December 1998 five centers enrolled 113 patients with stable or unstable angina and a single de novo lesion in vessel sizes > or = 2.75 mm. Procedural success was achieved in all 113 (100%) patients. During hospital stay one (0.88%) patient sustained a non-Q-wave myocardial infarction. Three patients died of a noncardiac reason during the 6-month follow-up. Quantitative coronary angiography (QCA) showed a minimal luminal diameter prior to intervention of 0.78 +/- 0.32 mm after PTCA 2.77 +/- 0.43 mm, and after 6 months a decrease to 2.06 +/- 0.76 mm, resulting in a loss index of 0.29 +/- 0.52 and a restenosis rate of 15.6% by QCA (n = 64) and 12.0% by visual estimation of additional 19 patients not suitable for QCA. The results of the Coroflex study demonstrated a low incidence of clinical events and complications and was combined with a low loss index and restenosis rate.