Approximately 310 000 Americans suffer from end-stage renal disease, with more than 70 000 new cases reported each year. Advances in immunosuppressive therapy for transplanted patients, in addition to the refined care of patients who are dependent on dialysis, have led to an improved survival for patients with renal failure. Structural, molecular, and pharmacologic developments continue to enhance the efficacy and safety of dialysis in the future. In addition, progressive improvements in the past 2 decades in organ transplantation, a greater insight into the immunobiology of graft rejection, and better surgical and medical management have resulted in improved outcomes. Although renal xenotransplantation is still in its early stages of development, additional research is leading this technology forward. Recent successes in harvesting and expanding renal cells in vitro and the development of biologically active synthetic materials allow for the creation of three-dimensional functioning renal units, which, in the future, may be applied ex vivo or in vivo for partial or full replacement of kidney function.