Objective: To assess the release and timing of matrix metalloproteinase-9(MMP-9)and inflammatory markers in patients taken coronary artery bypass grafting(CABG) with cardiopulmonary bypass(CPB) and off-pump coronary artery bypass surgery(OPCAB). Methods:Eighteen patients each subjected to coronary artery bypass grafting and off-pump coronary artery bypass surgery respectively were included in this study. In the CPB group,artery blood samples were collected for biochemical measurements at the following time points:immediately prior to the induction of anesthesia,15 min after initiation of CPB,termination of CPB,2 and 6 h after termination of CPB. In the OPCAB group,time points were as follows:T0,before induction of anesthesia;T1,after completion of anastomose of left anterior descending coronary atery;T2 after completion of all anastomoses;T3,at 2 h,T4,at 6 h after completion of all anastomoses. Results:The levels of MMP-9,TNF-α and IL-8 in CABG group were higher significant than in OPCAB group(P < 0.01). Concentration of MMP-9,TNF-α and IL-8 peaked at termination of CPB in CABG group(P < 0.01). The correlaton between MMP-9 and TNF-α,MMP-9 and IL-8 were significant(r,0.72 and 0.56,respectively). Conclusion:Cardiopulmonary bypass induced the release of MMP-9. TNF-α and IL-8 might amplify the release of MMP-9. The release of MMP-9 could contribute to the CPB-induced inflammatory reaction.