Introduction: Atherosclerotic renal artery stenosis (RAS) is associated not only with hypertension, ischemic nephropathy, and cardiac disease but also with a considerably increased cardiovascular mortality. Acute coronary syndrome (ACS) also carries a high risk for mortality, however, the correlation between angiograpically documented ACS and significant RAS has not been fully proven. Materials and Methods: We enrolled 476 patients that performed both coronary angiography (CAG) and renal arteriography between January, 2007 and June 2011. We analyzed renal arteriographic findings of ACS group (STEMI, NSTEMI, unstable angina) vs. non-ACS group. We defined significant RAS as ≥50% diameter stenosis. Results: 198 patents (41.5%) were included in ACS group (STEMI; n=60, NSTEMI; n=50, Unstable angina; n=88). The prevalence of significant RAS among total patients was 16.5% (n=79). Compared with non-ACS group (ACS group vs. non-ACS group), the significant renal artery stenosis (25.2%; n=50 vs. 10.4%; n=29, p<0.05) were more frequently found in ACS group. There was no additional procedure (renal areriography) related renal complication. Conclusion: In this study, when compared to patients with non-ACS, patients with ACS had more prevalence of significant RAS. The impact of this result to clinical outcomes has to be elucidated.