Objective: To investigate the protective effect of Dingxin Recipe (DXR) on arrhythmia and injury induced by ischemia and reperfusion. Methods: Rabbits were randomly divided into four groups and administered orally with DXR of high dose, low dose, propanolol and distilled water. Two-step coronary artery ligature was used to form ischemia and reperfusion model. Superoxide dismutase (SOD), cyclic adenosine monophosphate (cAMP), norepinephrine (NE), dopamine (DA), 5-hydroxytryptamine (5-HT), myocyte ultrastructural injury and occurrence of arrhythmia were investigated. Results: DXR could obviously antagonize arrhythmia induced by myocardial infarction or ischemia and reperfusion in rabbits. Compared with the control group, DXR of high and low doses could improve the changes in ST-T. In rabbits treated with DXR, the levels of SOD were elevated while cAMP, NE, DA, 5-HT and the whole blood viscosity were lowered. Conclusions: DXR could obviously antagonize arrhythmia and injury induced by ischemia and reperfusion, DXR may clear oxygen free radical, regulate the second messenger, inhibit sympathetic nerve system, improve local circulation, protect mitochondria and prevent the activation of lysosome and safeguard the cardiac myocyte to be free from injury. Objective: To investigate the protective effect of Dingxin Recipe (DXR) on arrhythmia and injury induced by ischemia and reperfusion. Methods: Rabbits were randomly divided into four groups and administered orally with DXR of high dose, low dose, propanolol and distilled water. Two -step coronary artery ligature was used to form ischemia and reperfusion model. Superoxide dismutase (SOD), cyclic adenosine monophosphate (cAMP), norepinephrine (NE), dopamine (DA), 5-hydroxytryptamine Results of arrhythmia were investigated. Results: DXR could obviously antagonize arrhythmia induced by myocardial infarction or ischemia and reperfusion in rabbits. Compared with the control group, DXR of high and low doses could improve the changes in ST-T. In rabbits treated with DXR , the levels of SOD were elevated while cAMP, NE, DA, 5-HT and the whole blood viscosity were lowered. Conclusions: DXR could obviously antagonize arrhythmia and injury induced by isc hemia and reperfusion, DXR may clear oxygen free radical, regulate the second messenger, inhibit sympathetic nerve system, improve local circulation, protect mitochondria and prevent the activation of lysosome and safeguard the cardiac myocyte to be free from injury.