Abstract: OBJECTIVE To illuminate the mechanism of tanshinone ⅡA on the prevention and treatment of myocardial ischemic/reperfusion(I/R) injury from the perspective of Notch signal pathway, the effect of tanshinone ⅡA on the level of MDA, cell apoptosis and the expression of Notch1, Hes1 and HIF-1α mRNA in the neonatal rat cardiac myocytes of I/R injury were studied. METHODS Culture the primary neonatal rat myocardiocytes, and establish a model of I/R injury according to previous reports. Four groups were settled, including control group, I/R model group, DAPT- treated group and tanshinone ⅡA-treated group. Myocardiocytes of I/R model group were incubated in DMEM medium for 1 h, then simulate ischemia for 2 h, after that DMEM medium were utilized for reperfusion for 4 h. DAPT-treated group were incubated with DMEM within DAPT for 1 h, then treated with the I/R injury procedure. Cells in tanshinone ⅡA-treated group were pretreated in DMEM medium with tanshinone ⅡA for 1 h, and simulate ischemia then reperfusion with DMEM. Production of MDA in myocardiocytes was tested by colorable reaction. Cell apoptosis was observed through Annexin V-PI staining. The activation of Notch signaling pathway and level of HIF-1α mRNA was detected by Real-time PCR. RESULTS Compared with control group, MDA levels in the myocardial cell of I/R model group rised (P<0.01), early cell apoptosis rate increased and the expression of Notch1, Hes1, HIF-1α mRNA were upregualted (P<0.05, P<0.01, P<0.01). Compared with I/R model group, MDA levels reduced(P<0.01), early apoptosis rate of myocardial cell decreased, the expression of Notch1, Hes1, and HIF-1α mRNA were downregulated(P<0.01) in the myocardial cell of DAPT-treated group and tanshinone ⅡA-treated group. CONCLUSION Chinese medicine monomer tanshinone ⅡA may protect neonatal rat cardiomyocytes from I/R injury through inactivate Notch pathway and regulating and cell apoptosis.