Introduction: Myocardial infarction is a pathology that presents high morbidity and mortality. It is the result of cardiomyocyte necrosis caused by oxygenation difficulties. Objective: The aim of this study was to review the histology of the myocardium and its histological changes when infarcted. Method: This is a narrative review of technical books and scientific articles published in SciELO and PubMed. Results: The myocardium is formed by cardiomyocytes, which contract due to the sarcomeres arranged in their myofibrils and present efficient electrical communication with each other through gap junctions. Myocardial infarction promotes the death of cardiomyocytes, alterations in cytoplasmic elements and electrical conduction, in addition to the formation of fibrous scar tissue. Conclusion: In conclusion, the myocardium is highly vascularized and formed by elongated contractile cardiomyocytes with a sarcometric composition. In ischemic conditions, such as myocardial infarction, there is histological remodeling in cardiac muscle tissue that leads to fibrosis and loss of contractile functions.