The complications, cost, and inconvenience associated with pretransplant hemodialysis and peritoneal dialysis would be minimized if transplantation were instituted without prior dialysis. That preuremic transplantation is safe and efficacious in patients with immanent end-stage renal disease has not been established. All 1742 consecutive primary renal transplants performed at the University of Minnesota during the 16.5 year period from January 1968 through July 1984 were reviewed to determine whether graft and patient survival were adversely affected by transplantation prior to dialytic therapy. In the overall group of primary renal transplants, no differences in actuarial graft or patient survival were noted with or without prior dialysis. Likewise, outcome was not affected by the pretransplant dialysis status in recipients of allografts from HLA-identical or mismatched living-related donors. However, in cadaveric transplantation graft function appeared to be adversely affected by transplantation prior to dialysis, with 52% vs. 66% two-year graft function for nondialyzed vs. chronically dialyzed recipients, respectively (P = 0.15). Patient survival was significantly (P =.04) decreased in the nondialyzed group, with 66% vs. 80% two-year survival in the chronic dialysis group. However, nearly all of the nondialyzed, cadaveric recipients were diabetic. The outcome of transplantation was found to be identical in these patients, as compared with chronically dialyzed diabetic recipients of cadaveric grafts. Thus, the apparent detrimental effect of predialytic transplantation in the cadaver group was due to the preponderance of diabetics in the nondialyzed group. Since July 1984, a single-armed therapeutic trial of combination therapy with azathioprine, prednisone, antilymphoblast globulin (ALG), and cyclosporine has been undertaken. Since that time, 36 primary graft recipients were transplanted prior to dialysis. Of these 36, 35 currently have a functioning graft. Thus, transplantation prior to chronic dialysis is safe irrespective of donor source, or choice of immunosuppressive agents.