Primary kidney transplants from living related and cadaveric donors to black recipients failed twice as rapidly as those to white recipients in data reported to the United Network for Organ Sharing Scientific Renal Transplant Registry between 1987 and 1991. The projected half-life for 132 HLA-identical sibling donor transplants in blacks was 15 years versus 29 years for 1,033 whites (P < 0.001). For recipients of cadaveric grafts, the half-lives were 5 years for blacks (n = 5,282) and 10 years for whites (n = 14,917). The 1-year graft survival rates and half-lives improved with HLA matching in both blacks and whites, but the 2-fold difference in long-term survival rates persisted even among recipients of well-matched grafts. With a zero HLA-A,B-mismatched donor, blacks had an 8-year half-life, compared with 17 years for whites (P < 0.001). The racial difference was most marked in young adults, with a 15-20% disparity at 3 years between blacks and whites aged 16-30. Pediatric and older black patients had 3-year graft survival rates similar to those of whites. Antilymphocyte globulin or OKT3 prophylaxis improved graft survival by 2% at 1 year and 5% at 2 years among blacks, but the half-life remained 5.6 years. In contrast to these findings in the United States, 63 blacks transplanted in Canada had the same short- and long-term graft survival as whites, suggesting an important long-term influence of the health care system and socioeconomic factors. In addition to improved access to health care and improved HLA typing of blacks, more black donors are needed to provide better matched transplants for blacks awaiting transplants.