Objective:To study the relationship of the changes of amount of neutrophils to concentration of IL-6,TNF-α during cardiopulmonary bypass. Methods:The serum levels of TNF-α,IL-6 were measured by Enzyme Linked Immunosorbent Assay(ELISA) method in patients undergoing heart valve replacement,and the amount of neutrophils was also measured. Serial blood samples were collected at the following intervals respectively:before CPB,40 min after CPB and 0 h,2 h,6 h,24 h after the end of CPB. Results:The serum levels of TNF-α,IL-6 and the amount of neutrophils after CPB were significantly higher than that before CPB(P < 0.01).The serum levels of TNF-α and IL-6 gradually increased after the beginning of CPB. The serum level of TNF-α reached the peak at 2 h after the end of CPB,and that still maintained a high level at 24 h after the end of CPB. The amount of neutrophils had the similar change. The serum level of IL-6 reached the peak at 6h after the end of CPB,then began to decrease but still higher than the concentration before CPB significantly. The concentration of TNF-α and IL-6 was correlated positively to the time of CPB and ACC(P < 0.01). There were correlations between the amount of neutrophils and the concentrations of TNF-α and IL-6. Conclusion:Cardiac surgery with cardiopulmonary bypass (CPB) leads to a systemic inflammatory response syndrome(SIRS) with secretion of cytokines and neutrophils. The time of CPB and ACC influences release of TNF-α and IL-6,so it may change the degree of SIRS in patients after operation. There are correlations between the amount of neutrophils and the concentrations of TNF-α and IL-6 during CPB.