The coronary system is the network of blood vessels that nourishes the heart muscle. After birth, proper coronary blood circulation is required to support heart homeostasis, and altered coronary function frequently leads to myocardial ischemia, infarction and heart failure. The epicardium plays a pivotal role during coronary blood vessel embryonic development, contributing cells to the coronary vasculature, but also secreting diffusible signals that regulate coronary morphogenesis and secondarily impact on ventricular compact myocardium growth. Accordingly, anomalous epicardium development gives rise to the multiple congenital defects of the coronary vascular system and the heart walls. In this review, we will summarize and discuss our current knowledge on the embryogenesis of coronary blood vessels, as related to epicardial development, and attempt to highlight the biomedical relevance of this tissue.