Cytotoxicity of glucose oxidase(GO) and neuroprotective effect of Aconiti Radix(AKR) against GO-induced neurotoxicity were measured for elucidating the mechanism of cardiotoxicity on cultured mouse myocardial cells by MTT assay after myocardial cells were cultured for 24 hours at various concentrations of GO. GO was toxic in a time-and dose-dependent manner on cultured myocardial cells after myocardial cells were grown for 24 hours in media containing 5～40mU/ml GO. While, cultures were pretreated with 50 μg/ml AKR for 2 hours increased remarkably cell viability. From the above results, it is suggested that GO is toxic on cultured mouse myocardial cells by the decrease of cell viability, and herb medicine such as AKR is very effective in the prevention of myocardial toxicity induced by GO.