Objective To investigate the relationship between insulin resistance and leptin in the perioperation of cardiac valve replacement.Methods Twenty patients were treated with cardiac valve replacement.Blood samples were obtained at the following intervals:before anesthesia,2 h,12 h,24 h and 48 h after cardiac valve replacement.The concentrations of leptin,insulin,hematokrit and blood glucose were measured.The insulin-resistance index (HOMA-IR),insulin-sensitivity index [1/ (INS × G)] and the ratio of insulin to blood glucose (I/G) were obtained.Results Insulin,blood glucose and HOMA-IR increased significantly from the beginning of anesthesia and went to the peak at 24 h after cardiac valve replacement (P ＜ 0.05).1/(INS × G) decreased significantly after anesthesia (P ＜ 0.05).Leptin level decreased gradually at the beginning and increased rapidly to the peak at 24 h after operation (P ＜ 0.01).HOMA-IR correlated well with leptin (r =0.958,P =0.010).Conclusions Insulin resistance exists in the perioperation of cardiac valve replacement.Correlation between leptin and insulin-resistance index indicates the role of leptin in insulin-resistance.