Human embryonic stem ceIIs(hESC),characterized by unique capacities of seIf-renewaI and differentiation into cardiomyocytes and hepatocytes,can be used in new drug screening and drug safety evaIuation processes. Cardiotoxicity and hepatotoxicity are major obstacIes to deveIopment and marketing of new drugs. hESC-derived cardiomyocytes and hepatocytes have structuraI and functionaI characteristics,which can be used for cardiotoxicity and hepatotoxicity testing in vitroand for buiIding a drug safety evaIuation system invitrothat has the advantage of short experiment cycIes,smaII dose,Iow cost and few species differences. hESC-derived cardiomyocytes and hepatocytes have broad prospects of appIication in toxicoIogy.