This study examined access to kidney transplant waiting lists and the allocation of cadaver kidneys to individuals who are waiting for a transplant. The authors found that blacks were almost 50 percent less likely than whites to be placed on a waiting list. This result held even after controlling for age, previous hospitalizations, primary cause of renal failure or geographic location of the patient. The authors also determined that patients in the southern half of the United States were less likely than those in many other regions of the country to be placed on a waiting list. However, they also found that blacks were 11.4 percent more likely than whites to be biologically incompatible with cadaver kidneys being retrieved, and this difference could explain all of the differences in waiting time to transplant between the races. Therefore, while access to cadaveric kidney transplant waiting lists remains a problem for black Americans, once on a waiting list biologic factors determine allocation decisions.