I.p. injection (5 g crude drug/kg) of water extract of Salvia miltiorrhiza to S.D. rats can prevent the acute cardial ischemia induced by the ligation of the coronary artery. The elevation of S-T segment in the electrocardiogram caused by the ischemia was greatly reduced in animals treated with Salvia miltiorrhiza compared with control group. The ischemia area in the left ventricle was significantly reduced and survival rate of the rats increased.