Abstract: ob＜x＞jective To explore the effects of FMS-like tyrosine kinase 3 (Flt3) gene transfection on ischemia reperfusion injury (IRI) in H9c2 rat cardiomyocytes in vitro . Methods The model of IRI was established and Flt3 gene carried by adenovirus was transfected into H9c2 rat cardiomyocytes. After the model was established, the effectiveness of Flt3 gene transfection was detected by immunofluorescence. The protein ex＜x＞pressions of Flt3 and Caspase-3 were tested by Western blotting . The viability of cardiomyocytes was detected by cell counting kit-8. And levels of lactate dehydrogenase (LDH), creatine kinase MB isozyme (CK-MB), maiondialdehyde (MDA) and superoxide diamutase (SOD) in supernatant of cell culture were measured by colorimetric method. Results In comparison with non-transfected groups, Flt3 protein ex＜x＞pression was higher and Caspase-3 protein ex＜x＞pression was lower significantly after transfection of Flt3 gene (P＜0.01)．The viability of cardiomyocytes upregulated in Flt3 transfected group (P＜0.01). After IRI, the levels of LDH, CK-MB and MDA were increased obviously , while the activity of SOD reduced in supernatant of cell culture(P＜0.05 or P＜0.01). However, the contents of LDH, CK-MB and MDA were lower in Flt3 transfected group than that in non-transfected groups while the activity of SOD was higher(P＜0.05 or P＜0.01). Conclusion Transfection of Flt3 gene can protect cultured H9c2 rat cardiomyocytes against IRI by inhibiting oxidative stress and reducing apoptosis probably