Aim To explore whether oxidative stress mediates doxorubicin-induced cardiotoxicity by inhibiting cystathionine-γ-lyase(CSE) expression and activity. Methods H9c2 cells treated with doxorubicin were used as the model of doxorubicin cardiototoxicity.H9c2 cells were pretreated with N-acetly-L-cysteine(NAC) 60 min prior to treatment with DOX so as to examine the role of oxidative stress in DOX-induced injury.Cell viability was measured by cell counter kit-8.The level of reactive oxygen species(ROS) was tested by dichlorfluorescein staining and photofluorography.Expression of CSE was detected by Western blot assay.Activity of CSE was examined by methylene blue test assay. Results Exposure of H9c2 cells to 5 μmol/L doxorubicin induced significant cardiotoxicity,leading to a decrease in cell viability.Doxorubicin not only enhanced ROS generation,but also inhibited CSE expression and activity in H9c2 cells.Pretreatment with NAC attenuated doxorubicin-induced ROS generation and cardiotoxicity,and also blocked the inhibitory effect of CSE expression and activity by doxorubicin. Conclusion ROS may mediate doxorubicin-induced cardiotoxicity by inhibiting CSE expression and activity.