Living unrelated donor (LURD) transplants have immunologic barriers similar to cadaver transplants, yet the outcome is better (1-year graft survival = 96%). One advantage of LURD transplants is that, with the extremely short preservation time, the kidney functions immediately. We studied whether the quality of initial renal function affects the outcome of primary cadaver transplants. We divided 301 non-6-antigen-matched recipients transplanted between 1/1/86 and 8/1/92--who had no graft loss due to hyperacute rejection, primary nonfunction, or technical reasons--into 5 groups based on the quality of initial renal function (serum creatinine level in the first week). We determined patient and graft survival rates for each group. We found that the quality of initial function had a significant effect on patient and graft survival rates. Recipients whose serum creatinine level was < 3 mg/dl on posttransplant day 5 (groups 1 and 2) had better patient and graft survival than either those whose serum creatinine level was > 3 mg/dl on day 7 (group 4) or those who required dialysis (group 5). Because some early dysfunction may be immunologic, we reanalyzed the data excluding patients with percent reactive antibody > or = 15; the quality of initial function in this group had a significant impact on outcome. Similarly, when patients with graft loss due to "death with function" were excluded, the quality of initial function had a significant impact on survival rates. We conclude that the quality of early posttransplant function is an important predictor of long-term outcome. Cadaver recipients with immediate good function have outcomes similar to living donor recipients. Our data suggest that increased effort should be made to improve immediate posttransplant function.