Heart regeneration is a complicated and intricate process that differs among different species and stages of development. In adult mammals, such as rodents, pigs, primates, and humans, myocardial injuries result in significant damage to the heart, leading to fibrosis and, in some cases, heart failure. Regenerating and repairing the heart presents a significant challenge. This chapter aims to provide a comprehensive summary of recent research that focuses on understanding the mechanisms behind the proliferation and regeneration of cardiomyocytes, the role of other cell types in cardiac regeneration, and the different strategies implemented to remuscularize the injured heart.