Is the world on the edge of a medical game-changer? After decades of false starts, scientists are beginning to believe that modified organs from animals could be used in the organ transplant process. Clive Cookson explores the fascinating world of xenotransplantation. Here, he contemplates how a new era of medical innovation, led by advances in gene editing, could help solve the global shortage. But is it a revolution or a stop-gap for a world with an increasing need for organs?