Abstract: OBJECTIVE To observe the effect of Lemai granules on model rats with myocardial ischemia and explore its mechanism. METHODS 48 male SD rats were randomly divided into six groups: normal group， model group， positive control group （Wenxin granules group）and high， middle and low dose group (0.84， 0.42， 0.21 g/kg) of Lemai granules. Myocardial ischemia rats model was established by intraperitoneal injection of isoproterenol (ISO)， and then different doses of Lemai granules were administered intragastrically to the myocardial ischemia rats for 7 d. The changes of the ST-segment of Ⅱlead electrocardiogram (ECG) was observed. The activities of CK， LDH and SOD， the content of MDA， NO， ET， IL-1β，TNF-α and CRP in serum were measured， and changes of blood rheology were tested. RESULTS ST-segment and the activities of CK and LDH of Lemai granules groups(0.84 g/kg， 0.42 g/kg， 0.21 g/kg) were lower obviously than that of model group (P<0.01). Compared with the model group， the activities of SOD and NO in Lemai granule groups of the high and middle doses (0.84 g/kg and 0.42 g/kg) increased in various degrees， while the levels of MDA， ET， IL-1β， TNF-α and CRP were decreased (P<0.05~0.01). The blood rheology were improved significantly. CONCLUSION Lemai granules shows promising protective effects on myocardial ischemia and its mechanism may be related to antioxidant action， regulation of endothelial cells， anti-inflammatory effects and blood rheology improvement.