Here was investigated the effect of Radix Astragalus Membranaceus IAM) on Caz influxacross the myocardial plasma membrane and coxsackie virus B3 ( CVB3 ) -RNA replication in cultured neonatalrat heart cells infected with CVB3 . It was found that the Oa2 intlux could be inhibited signiticantly by AM bothin heart cells intected with CVB3 for 48 hours and in normal control heart cells. In addition. the Caz intluxand the amounts of CVB3-RNA in rnyocytes simultaneously intected with CVB3 and treated with AM for 48hours were statistically decreased compared with that in CVB3-infected contrOI cells. These phenomena sug-gested that AM could exert the effects of decreasing the secondary Ca2 damages, irnproving the abnormalmyocardial electric activity and inhibiting replication of CVB3-RNA in myocardium. Thus, it is a rationalchoice to treat patients with AM in viral myocarditis.