“…For example, after transferring spleen cells of CBA mice into A line mice within 24 hours of birth they were able to show that the CBA cells persisted into adult life and that these A mice would accept grafts from CBA mice without rejecting them-an example of artificial chimerism.2 This tolerance did not appear to be organ specific in any way Chronic renal failure was a logical disease in which to attempt to use this new knowledge because of the usual hopelessness of the situation, the relatively straightforward technical problem, the availability of the' artificial kidney and the fact that the recipients' own kidneys could be left in place. The reports of Hume et al in 1952 and1955 in this country3 as well as those of Kiiss et al in 19514 and of Michon et al in 19535 in France marked the beginnings of serious efforts to accomplish successful renal homotransplantation in man. Numerous technical problems have now been overcome, and progressively longer survivals have been achieved, resulting, in a few rare instances, of almost complete reversal of uremia and hypertensive vascular disease.…”