Abstract: Myocardial infarct was produced by occluding the apical branch of the left anteriordescending coronary artery. The effect of the corolla extract of Flos Carthami, the Chinese medicinal plant "Hong-Hua", on the extent of myocardial ischemia was evaluated by means of the epicardial electrographic mapping. During the 15 rain-occlusion the mapping was performed in 5 min interval, then the coronary occlusion was released. After reperfusion for 1 hr, while the Hong-Hua extract was being infused, a second occlusion and mapping was applied again as before@Hong-Hua extract (25%) in a dose of 2 g/kg reduced the average ST segment elevation. In the central infarct zone, 15 min after the first and second occlusion were 7.5±0.6 and 3.3±0.5mV respectively (P<0.001), whereas in the border zone the correspoding values of were 3.5±0.4 and 0.9±0.2mV(P<0.001). Reduction of was more Significant in the border zone than in the central zone (P<0.001).@Hong-Hua extract administered during the second occlusion markedly reduced the number of sites showing equal or greater than 2 mV ST segment elevation (NST) in the border zone as compared with occlusion alone, but NST remained unchanged in the central zone.@After administration of Hong-Hua extract, heart rate decreased from initial value of 164±11 to 144±9 beats/min (P<0.05) and tension-time index from 129.0±6.3 to 116.8±6.3 (P<0.01).@Our data suggest that Hong-Hua may reduce the infarct size following acute coronary occlusion by salving a lot of jeopardized myocardium in the border ischemic zone, and that the reduction of myocardial oxygen consumption was involved in the beneficial action of Hong-Hua.