Previous studies of the effect of donor factors on renal transplant outcomes have not tested the role of recipient body mass index, donor/recipient weight ratios and age matching, and other factors. We analyzed 20,309 adult (age 16 or older) recipients having solitary cadaveric renal transplants from adult donors from 1 July 1994 to 30 June 1998 in an historical cohort study (the 2000 United States Renal Data System) of death censored graft loss by the Cox proportional hazards models, which corrected for characteristics thought to affect outcomes. The only independently significant findings in Cox Regression analysis were a high donor/ recipient age ratio (> or = 1.10, e.g. a 55-year-old donor given to a recipient age 50years or younger, adjusted hazard ratio (AHR) 3.22, 95% confidence interval (CI) 2.36-4.39) and African American donor kidneys (AHR 1.64, 95% CI, 1.24-2.17). African American recipients and older donors were not at independently increased risk of graft failure in this model. Among donor factors, older donor kidneys given to younger recipients and donor African American kidneys were independently associated with graft loss in recipients of cadaver kidneys. The task for the transplant community should be to find the best means for managing all donor organs without discouraging organ donation.