Fisetin improved the myocardial function by alleviating cardiac dysfunction, ameliorating myocardial fibrosis, mitigating cardiac hypertrophy in DOX-induced rats, and increasing the expressions of SIRT1/Nrf2 pathway genes, HO-1 and FTH1, in rats and H9c2 cells. This evidence concerns the gene SIRT1 and Myocardial fibrosis.