Background: Mild renal dysfunction may be associated with increased cardiovascular morbidity and mortality. Methods: The relation between estimated glomerular filtration rate (eGFR), as calculated from plasma creatinine at admission, and coronary artery disease burden (CADB), was studied in a cohort of 110 patients with acute coronary syndrome and coronary atherosclerosis. Results: A relatively weak but significant negative correlation was found between eGFR and CADB as measured by angiography (coefficient correlation of -0.26, probability value of 0.006); a similar association was seen in multiple regression analysis, taking CADB as dependent variable, and eGFR, age, plasma calcium and plasma phosphorus as independent variables. After dividing the 110 patients into eGFR tertiles (with mean values of 102.9 +/- 22.8, n = 37, 75.7 + or - 5.6, n = 36, and 53.1 +/- 13.4, n = 37, all in mL/min per 1.73 m(2)), mean CADB values of the lower and higher eGFR tertiles were found to be significantly different (270.6 +/- 176.4 and 192.9 +/- 78.5, respectively). Similar mean values for CADB and for eGFR were noted when patients with elevated ST segment/new left bundle branch block and patients with nonelevated ST segment acute coronary syndrome were compared. Conclusions: We conclude that renal function of patients with acute coronary syndromes and coronary atherosclerosis, as estimated at admission, is negatively correlated with coronary artery disease burden. It is unknown whether renal dysfunction acts as a cause for accelerated coronary artery disease or if it merely acts as a surrogate marker for the overall systemic vascular system status.