This chapter begins with an introduction to transplant surgery with its intriguing history and development as a specialty. The general principles of biological rejection are covered on a background of immunology and immunosuppression. Clinical transplants in children are detailed with the first and most well-established being renal transplantation . The causes of end-stage renal failure are listed with further details of preparation, the operation itself, and potential complications. Cardiac transplantation is fully discussed, including indications, contraindications, the role of mechanical support, surgery for the donor and the recipient, complications, and postoperative management. Liver transplantation is covered in detail, including listing for a transplant, choice of a suitable donor, the surgical procedure, and outcomes and complications. Finally, intestinal transplantation is covered with discussion on indications, potential complications, and outcomes.