Abstract: Objective: To investigate the changes and the clinical value of biochemical markers of myocardial damage in patients undergoing operation of heart valve replacement.Methods: The creatine kinase(CK),creatine kinase-MB(CK-MB),cardiac treponin I(cTnI),C reactive protein(CRP),lactate dehydrogenase(LDH) and hydroxybutyrate dehydrogenase(HBDH) in 40 patients receiving heart valve replacement were measured before operation,instantly after extracorporeal circulation,and at 6,24,48,72 hour and 6 days after the operation,and the changes were analyzed.Results: All the biochemical markers of myocardial damage were within normal limits except CRP before operation.The figures of cTnI and CK-MB increased significantly at 6 hour after operation(P<0.01).Aspartate aminotrans ferase(AST),LDH and HBDH rose significantly at 24 hour after operation.CRP reached the peak at 48 hour after operation.The two variables of cTnI and CK-MB in serum showed a positive linear correlation and had a higher correlativity comparable to other markers.Conclusions: All the biochemical markers of myocardial damage present abnormal changes successively during the perioperation of cardiac valve replacement.Monitoring the myocardial biochemical markers can decrease sudden death and incidence of other cardiac events.