Background and Objectives竊� Nicorandil has the pharmacologic effects similar to currently-taken nitrate and in respect to the potassium channel opening action in vascular smooth muscle cells, and the frequency of use of the agent is being increased. But, there was no report as early therapeutic agent for acute myocardial infarction. We examined the prophylactic effect against major adverse cardiac event(MACE) and side effect of nicorandil after administration for the patients who had acute non-ST segment elevation myocardial infarction(NSTEMI), which was analyzed under comparing with nitrates. Subjects and Methods竊� A total of 67 patients (34 nicorandil administration group, 33 nitrates intake group) who had chest pain originated from acute NSTEMI on admission into emergency room were enrolled and randomized in this study. All patients in both group underwent coronary angiography / percutaneous coronary intervention during hospitalization, and follow-up after discharge was performed at OPD on 1st, 3rd, & 6th months. We investigated the frequency of MACE and adverse effect of used agents. Results竊� There was no demonstrable difference of clinical profile between both group. The result of comparative analysis revealed slight decrease of reinfarction rate in nicorandil group without statistical significance(2.9% versus 9%, p value = 0.076), and no meaningful difference on aspect of target vessel revascularization and cardiac-origin death. No ominous distinction of frequency of the adverse drug effect was noted in both group. Conclusion竊� In spite of statistical insignificance, the early use of nicorandil for acute NSTEMI may reduce in-hospital reinfarction incidence. The other profile showed no notable advantage compared with nitrates. Because of a small number of enrolled patient, further large randomized trials are needed for evaluation of favorable effect of nicorandil.