Background This study aimed to clarify the effect of Reopro짰 and combined adenosine and nicorandil administration in patients who developed no-reflow phenomenon during percutaneous coronary intervention (PCI). Methods One hundred eights patients who developed no-reflow phenomenon during PCI for acute coronary syndrome between January 2005 and December 2005 comprised the study group were divided into 2 groups: Group I [53 patients, 67.3짹9.3 years, 33 male; combined intracoronary adenosine (24關g/ml) and nicorandil (2 mg/ml)] and group II [55 patients, 65.3짹13.8 years, 40 male; Additional administration of Reopro짰 (0.25mg/kg) to the combined intracoronary adenosine and nicorandil]. In-hospital and 6-month major adverse cardiac events (MACE) after PCI were compared between the tow groups. We performed subgroup analysis of group II, who were subdivided into 2 subgroups: Group IIa [20 patients, 66.4짹13.0 years, 14 male; Reopro짰 administration prior to PCI], Group IIb [35 patients, 64.7짹14.5 years, 26 male; Reopro짰 administration after the development of no-reflow]. Results Clinical diagnosis and risk factors of coronary disease, left ventricular ejection fraction were not significantly different between the 2 groups. Number of involved vessels, lesion type according to ACC/AHA classification and TIMI flow grade (TFG) were not significantly different in both groups. The diameter and length of stents were not significantly different. TFG after PCI, difference in TIMI frame count (TFC) before and after PCI, in-hospital and 6-month MACE were not significantly different. All variables between Group IIa and IIb were not significantly different but, in-hospital MACE was different between Group IIa and IIb [Group IIa:IIb=0(0%):5(16.7%), p=0.028, two death and three target lesion revascularization in Group IIb). Conclusions Routine administration of Reopro짰 before PCI can improve clinical outcome in ACS patients.