BACKGROUND AND OBJECTIVES: Stent implantation for coronary ostial lesions is challenging. This study evaluated the feasibility, safety, and immediate procedural results of the Osfit™, innovatively designed sirolimus drug-eluting stent delivery system for the treatment of coronary ostial lesions. METHODS: The Osfit™ has a 5 mm long extended balloon proximal to the stent (bare balloon without mounted stent). When inflated at 1.5 atm, only bare balloon inflated and acts like a stopper. We evaluated the technical feasibility in 49 patients with a coronary ostial lesion (defined as stenosis within 3 mm from the origin of the vessel) who had received the Osfit™. Intravascular ultrasound (IVUS) analysis was done in 11 patients who consented to IVUS examination, and the depth from the proximal edge of the stent to the ostial plane (DSO) was measured. RESULTS: In all 49 lesions, stents were successfully implanted in one single angiographic view without obvious stent protrusion or definite angiographic missing of the ostium. The proportions of aorto-ostial, and bifurcation lesions were 28.6% and 71.4%, respectively. The DSO was 0.2±0.69 mm, and the proximal stent edges were located within 1 mm of the ostial edge in all patients. No adverse events like death, myocardial infarction, target lesion revascularization, target vessel revascularization or stent thrombosis were reported during the in-hospital period or within 30 days. CONCLUSIONS: The implantation of the Osfit™ for coronary ostial lesions appears to be an accurate and safe procedure that may reduce multiple angiographic projections and advanced skills.