The total number of cadaveric kidney transplants has been declining, despite an increasing dialysis population, greater understanding of transplant immunology, and improved transplant management. To explore the causes of this decline, various factors were studied in 140 dialysis patients who were awaiting transplantation and 100 consecutive recipients of cadaveric kidney transplants. The study indicates that there is a growing, now predominant, prospective kidney recipient population that is highly sensitized because of previous blood transfusions and kidney transplantations. As a result, 92% of the prospective recipients exhibit varying degrees of lymphocytotoxic antibodies. Thus, a major problem in clinical transplantation is the growing number of dialysis patients who are virtually untransplantable. The declining number of cadaveric kidney transplantations may be caused by, in part, changing immunologic characteristics in the recipient population.