BACKGROUND: Renal dysfunction or acute renal failure in patients undergoing coronary artery bypass grafting (CABG) is an important cause of morbidity and mortality. The great impact of acute renal failure (ARF) in the outcomes of cardiac surgery demands its study in our population, encouraging to the elaboration of this study, which aimed to identify the incidence and risk factors of ARF after CABG. METHODS: Since March 2010 to 2011, 589 patients were studied who underwent CABG in Sina Hospital (Isfahan, Iran). In this cross-sectional study, patients were divided into two groups based on the occurrence of ARF after CABG and measured variables were compared between the two groups was also statistically significant. P value less than 0.05 was set as a significant level. RESULTS: A total of 434 men and 155 women were enrolled in the study. The mean age of the study subjects was 57.6 years. ARF was seen in about 22% of patients after CABG. The mean age of ARF group was more than 3 years higher than that in the other group and the difference was significant between the two groups. Serum creatinine level after the surgery was different between the two groups. Moreover, the history of diabetes mellitus was significantly different between the two groups. Pump time comparison also showed was also statistically significant. CONCLUSION: Our data showed older patients were more prone to affected by ARF. In addition, diabetic patients should be considered as high risk patients and are more likely to deteriorate by ARF. Despite increased prevalence of renal insufficiency in CABG patients, studies show that in most cases, this is not a serious problem and it is easily treatable. A lower proportion of patients (1.0 to 1.7% in different large series) develop ARF severe enough to require dialysis. Keywords: Coronary Artery Bypass, Acute Kidney Injury, Creatinine </span