Doxorubicin-induced cardiac toxicity has been a major concern of oncologists and is considered the main restriction on its clinical application. Oxymatrine has shown potent anti-cancer, anti-fibrosis, and anti-oxidative effects. Recently, it has been reported that oxymatrine is protective against some cardiovascular diseases. In this study, we aimed to investigate the effects of oxymatrine on doxorubicin-induced cardiotoxicity in rat hearts and H9c2 cells.