The cardiovascular system is the first functional organ system to develop within the mammalian embryo. During the early stages of cardiovascular development, the heart and blood vessels undergo rapid growth and remodeling required for embryo viability, proper morphogenesis, and the function of all organ systems. Live imaging of these dynamic events in early mouse embryos is critical to understanding when and how these morphological changes occur during normal development and how mutations and pharmacological agents affect cardiovascular structure and function in vivo. The use of optical coherence tomography (OCT) allows for rapid, three-dimensional structural and functional imaging of mouse embryos at cellular resolution without the aid of contrast agents. In this chapter, we will describe how OCT can be used to assess the morphology of vessels and the heart, dynamic analysis of cardiac function, and hemodynamics within extraembryonic and embryonic blood vessels.