The present invention elates to the applications of neuregulin in the preparation of drugs for preventing, treating or delaying the ischemia-reperfusion injury (IRI) in mammals, particularly in humans. In particular, the present invention provides the neuregulin based compositions and methods for preventing, treating or delaying the myocardial ischemia-reperfusion injury. Specifically, although it has been shown in cytological experiments, animal studies and clinical trials that neuregulin can improve the cytoskeleton structure of myocytes and cardiac function, it is still unknown whether neuregulin has effects on the myocardial ischemia-reperfusion injury. The present invention proves that neuregulin reduces the infarction size in the rat IRI model, which indicates that neuregulin can be used for preventing, treating or delaying the myocardial ischemia-reperfusion injury
