More than 25% of the kidneys that are recovered from deceased donors in the U.S. and are offered to patients on national waiting list are not utilized.

We discuss how waiting list designs can suffer from a form of congestion that can lead to discarding valuable organs. Congestion arises from the interaction of a physical limit on the number of patients that can sequentially consider an organ before it accrues excess cold ischemic time while patients have the incentives to obtain organs of high quality.

We develop a framework to study equilibria of waiting lists with congestion and show that congestion provides a strong enough externality to substantively affect welfare and wastage.

We further show how practical features in waiting lists can affect congestion, including recent design changes, and discuss policies and market designs that can mitigate congestion.