Abstract: AIMTo study the protective effect of hyperin on the apoptosis in rat cardiomyocyte induced by ischemia and reperfusion injury. METHODSThe apoptosis in myocardium was subjected to 30 min coronary occlusion followed by 3.5 h of reperfusion in male Sprague-Dawley rats. It was provided by 6 h of anoxia followed by 24 h of reoxygenation in the cultured neonatal rat cardiomyocytes. The profile of apoptotic myocardium was observed by phase-contrast microscope, fluorescent micrograph and terminal deoxynucleotidyl transferase mediated dUTP-digoxigenin nick end-labeling (TUNEL) method. The apoptotic number in cardiomyocytes was examined by transmission electron microscopy and flow cytometry. RESULTSIn the apoptosis myocardium of ischemia/reperfusion rat, hyperin (25, 50 mg·kg^-1) was shown to inhibit the increase of apoptotic cells of the myocardium (P<0.05, P<0.01); hyperin was (0.5～50.0 μmol·L^-1) also shown to significantly decrease the percentage of apoptotic cells in cultured neonatal rat cardiomyocyte. CONCLUSIONHyperin may have protective effect against cardiomyocyte ischemia/reperfusion injury. Cardiomyocyte apoptosis may be involved in the mechanism.