The organ transplant system in the United States is a complex system designed to allocate the limited resource of donated organs to the more than 100,000 individuals awaiting life-saving transplants. A set of organ allocation policies aims to provide the donated organs to the recipients in need in a predetermined order to achieve a set of principles guided by federal regulations. In this seminar, we will delve into the intricacies of the organ donation and transplantation system in the United States and examine how the field of epidemiology contributes to the ongoing evaluation and enhancement of this system.