The beneficial effects of pretransplant blood transfusions on the success rate of renal transplantation have been so overwhelmingly emphasized that there is virtually no information on the fate of grafts in nontransfused patients transplanted during the last decade. Since 1979, all patients who have undergone renal transplantation at the University of Minnesota have routinely received random blood transfusions except Jehovah's Witnesses. Jehovah's Witnesses refuse transfusions but will accept renal allografts. From 1979 to May 30, 1987, primary renal allografts were placed in thirteen nontransfused Jehovah's Witnesses; six patients received kidneys from mismatched living-related donors, two patients received HLA-identical sibling grafts, and five patients received cadaveric renal allografts. The range of follow-up of the thirteen patients was 3-93 months, with a mean of 45 months and a median of 50 months. The outcomes after renal transplantation in Jehovah's Witnesses were compared with those of a paired control group (n = 25) matched for age, date of transplant, donor source, and diabetic status. The overall three-year actuarial patient and graft survival rates of the Jehovah's Witnesses were 83 per cent and 66 per cent, versus 80 per cent and 77 per cent for the controls. Although the outcomes after renal transplantation in Jehovah's Witnesses were similar to those of the control group, the Jehovah's Witnesses had an increased susceptibility to rejection episodes. The cumulative percentage of incidence of primary rejection episodes was 77 per cent at three months in the Jehovah's Witnesses versus 44 per cent at 21 months in the matched control group. The consequence of early allograft dysfunction from rejection was particularly detrimental to Jehovah's Witnesses who developed severe anemia (hemoglobin (Hgb)* 4.5 g per cent)-two early deaths occurred in the subgroup with this combination of problems. The overall results suggest that renal transplantation can be safely and efficaciously applied to most Jehovah's Witnesses but those with anemia who undergo early rejection episodes are a high-risk group relative to other transplant patients.