Abstract: Objective: To study the protective effects of sufentanil preconditioning on myocardial ischemia-reperfusion injury induced by cardiopulmonary bypass(CPB) in cardiac valve replacement patients. Methods: Forty-five patients scheduled for elective cardiac valve replacement with CPB were randomly divided into three groups(n=15),control group(group A),patients received 3 episodes of 5 minutes normal saline infusion at 1 ml/min at 5 minutes interval before aorta clamping; low-dose sufentanil preconditioning group (group B) and high-dose sufentanil preconditioning group(group C) patients that received 3 episodes of 5 minutes sufentanil infusion at 0.2,0.4 μg·kg^-1·min^-1 at 5 min interval before aorta clamping,respectively. Plasma levels of cardiac troponin I(cTnI) and creatine phosphokinase isoenzyme(CK-MB) before induction of anesthesia(T₁),4(T₂),8(T₃),24(T₄) and 48 hours(T₅) after aorta unclamping were measured. The hemodynamics and postoperative assistant ventilation,24 hours postoperation contraction score,drainage volumn and stay in the intensive care unit were also recorded. Results: In group A,plasma cTnI levels at T₂,T₃,T₄ and T₅ were higher than that at T 1 (P < 0.01),reached the peak level at T₃,then declined at T₄. In group B and C plasma cTnI levels at T₂,T₃,and T₄ were higher than that at T₁ (P < 0.05-P < 0.01),and reached the peak level at T₂,then declined to normal range at T₅. Plasma cTnI at T 2,T₃,T₄ and T₅ in group B and C were lower than that in group A(P < 0.05-P < 0.01),respectively. Plasma CK-MB levels at T₂, T 3,T₄ and T₅ were higher than that at T₁ in three groups(P < 0.05-P < 0.01). There were no significant differences in plasma CK-MB levels among three groups at T₂,T₃,but the values were lower in group B and C than that in group A at T₄,T₅ (P < 0.05-P < 0.01). Intubation time, the requirement for inotropics, the volume of wound drainage in first postoperative day and ICU stay time in group B and group C were significant less than that in group A. Conclusions: Sufentanil preconditioning could relieve myocardial injury induced by CPB in cardiac valve replacement patients.