Abstract： Objective To observe the significance of the changes of cell adhesion molecules (CAM) CD11b/CD18 and sPselectin during the perioperative period of open heart surgery under cardiopulmonary bypass (CPB), and investigate the roles of CD11b/CD18 and sPselectin in systemic inflammatory response triggered by CPB. Methods Thirty patients including 18 males and 12 females, age ranged from 29 to 55 years (45.3±8.1 years) having undergone valvular replacement for rheumatic heart disease in our hospital were selected as the subjects of this research. After anesthesia induction, radial arterial blood sample was collected at six different time points including the time prior to skin incision, and 30 min, 1 h, 6 h, 12 h and 24 h following the start of CPB. The expression levels of CD11b/CD18 were tested by flow cytometry, and concentration of sP-selectin in the plasma was measured with enzymelinked immunosorbent assay(ELISA). Results The expression of CD11b/CD18 was elevated at 30min after CPB, and it reached the peak (581.44±215.26) at 6 h after CPB with significant differences (Plt;0.05). Its expression started to drop at 12 h after CPB, but it was still higher than the expression level before CPB. The expression returned under the level before CPB at 24 h after CPB with insignificance differences (Pgt;0.05). The expression of sPselectin in the peripheral blood started to rise evidently at 30 min after CPB, reaching the peak (51.44±10.06 ng/ml) with significant differences (Plt;0.05). Its expression level decreased at 12 h after CPB and fell back below the level before CPB with insignificant differences (Pgt;0.05). Conclusion CPB can cause the expression of CD11b/CD18 and sPselectin to rise in the peripheral blood, which may play an important role in the systemic inflammatory response triggered by CPB.