Purpose of Review In this review, we aim to summarize and discuss the cellular origins of the coronary endothelial cells during development and neovascularization in the adult stage after cardiac injury. Recent findings Recent work identified three different developmental origins for coronary endothelial cells: proepicardium, endocardium, and sinus venosus. However, the level of contribution by each source remains debated. During heart injury and regeneration, although multiple cell types such as endothelial progenitor cells, epicardial cells, and endocardial cells were reported to contribute neovascularization, convincing evidence is still lacking.. Recently, fibroblasts were reported to contribute to endothelial cells after cardiac injury through mesenchymal-to-endothelial transition. A subsequent study demonstrated that pre-existing endothelial cells mainly mediate cardiac neovascularization after injury. Summary The developmental origins of coronary vessels are diverse and further studies are needed to address the exact contribution from each source and the molecular mechanism governing distinct vessel formation programs. In the adult stage, neovascularization is mainly mediated by the pre-existing endothelial cells, with negligible contribution from other sources.