Objective To discuss the protective effect of intra-aortic balloon pump(IABP) on renal function in patients with chronic renal insufficiency undergoing cardiac operations.Methods From May 2010 to May 2012,17 patients with moderate renal insufficiency who underwent cardiac surgery using cardiac pulmonary bypass(CPB) were randomized to divide into IABP group and control group.IABP was inserted before the cardiac operation,the support was maintained perioperatively in IABP group.In control group the IABP was never used during the operation.The clinical parameters related to renal function including the output of urine,the serum creatinine levels were documented perioperatively.Results The serum creatinine levels were increased obviously post-operation in both groups.But the degree of increase was significantly smaller in IABP group.Conclusion To patients with moderate renal insufficiency undergoing CPB cardiac operations,perioperative application of IABP is beneficial to protect renal function and may help to improve the outcome.