Book excerpt: Injured mammalian hearts do not regenerate but scar. This is a major medical problem, as ischemic heart disease is among the leading causes of morbidity and mortality worldwide. Essential clues for human heart repair are uncovered when zebrafish and newt are found to regenerate cardiac muscle after injury.This book presents the major advances of the last decade in the field of cardiac regeneration. These recent advances include: demonstration that zebrafish, a genetically tractable system, can regenerate heart; the identification of several new stem cell populations in the heart; demonstration that stem cells can be used to improve heart function; and demonstration that induction of cardiomyocyte proliferation is a realistic future option to repair injured hearts. This book also provides detailed reviews of the research on model organisms capable of heart regeneration as well as innovative translational research to achieve regeneration in mammals, that comprises work on blood born stem cells, endogenous cardiac stem cells, paracrine factors, reawakening of cardiomyocyte proliferation, and bioengineering. More importantly, the book, in the concluding chapter, dovetails the studies with a comprehensive overview of clinical trials.