Objective To investigate the prognosis and risk factors of cardiac surgical patients with preoperative renal dysfunction，and evaluate the accuracy of estimated glomerular filtration rate （eGFR） as a predictor of adverse outcomes. Methods A total of 2 151 adult patients undergoing cardiac surgery in Renji Hospital，School of Medicine of Shanghai Jiaotong University from January 2005 to December 2009 were included in this study. There were 1 267 male patientsand 884 female patients with their average age of 58.7 （18-99）years. Clinical characteristics of patients with preoperative renal dysfunction，severity of postoperative acute kidney injury （AKI）and patients’ outcomes were analyzed. Multivariate logistic regression was performed to analyze perioperative risk factors of postoperative AKI. Receiver operating characteristic（ROC） curve was used to evaluate the accuracy of eGFR to predict patients undergoing postoperative renal replacement therapy （RRT） and in-hospital death. Results A total of 221 patients （10.27%） had preoperative renal dysfunction，among whom 124 patients （56.11%） developed postoperative AKI. Patients with preoperative renal dysfunction were older，had more comorbidities including hypertension and diabetes mellitus，were more likely to receive postoperative RRT，and had worse outcomes. Patients with decreased preoperative eGFR had significantly higher in-hospital mortality. Patients with preoperative renal dysfunction who developed postoperative AKI had the worst prognosis. Multivariate logistic regression showed that hypertension （OR=4.497，P=0.003），postoperative central venous pressure （CVP） ＜6 cm H2O （OR=16.410，P=0.000） and postoperative CVP＞14 cm H2O （OR= 5.178，P=0.013） were independent predictors of postoperative AKI for patients with preoperative renal dysfunction. The areas under the ROC curves of eGFR to predict in-hospital mortality and postoperative RRT were 0.691 and 0.704 respectively （95% CI 0.630-0.752，P=0.000；95% CI 0.614-0.795，P=0.001）. Conclusion Patients with preoperative renal dysfunction are older，have more comorbidities，higher likelihood to develop postoperative AKI and worse prognosis. Hypertension，postoperative CVP＜6 cm H2O and postoperative CVP＞14 cm H2O are independent predictors of postoperative AKI for patients with preoperative renal dysfunction. We believe eGFR can accurately predict the risk of adverse kidney outcomes and in-hospital death of patients undergoing cardiac surgery.