Due to the shortage of cadaveric organs, kidneys from living unrelated donors (LUD) are increasingly being used for transplantation. The long-term outcome for LUD recipients is not completely known. This study was undertaken to evaluate the long-term graft survival in LUD recipients and compare it with that of cadaver donor allograft recipients. Three hundred and sixty-four LUD and 3881 cadaveric kidney recipients were evaluated using data obtained through the Brazilian Renal Transplant Registry. Transplants performed between January 1, 1987, and June 30, 1996, were eligible for analysis. Graft and patient survival were estimated by the Kaplan-Meier method. Sixty percent of the LUD were from spouses. The median duration of follow-up was 23.8 mo (0 to 117.2 mo). Patient survival rates were not significantly different for LUD and cadaveric kidney recipients (69% [95% confidence interval (CI), 61.9 to 76.1%] versus 73.2% [71 to 75.4%] at 5 yr; 69% [61.9 to 76.1%] versus 60.6% [55.1 to 66.1%] at 9.6 yr). Graft survival rates for recipients of LUD allografts were similar to those for cadaveric kidneys at 5 yr (50.1% [43.2 to 57%] versus 50.4% [48.1 to 52.8%]) and higher, although not significantly, at 9.6 yr (45.7% [37.7 to 53.7%] versus 32.7% [26.4 to 39%], respectively, P = 0.14). In a multivariate analysis using the Cox proportional hazards regression model, after adjusting for recipient age, race, history of previous transplantation, and year of transplantation, the risk of graft failure was 16% (95% CI, -3% to 31%) lower for LUD than cadaveric recipients. We conclude that LUD are an excellent alternative to cadaveric kidney donors. The long-term patient and graft survival rates for recipients of LUD allografts are at least as good as those for recipients of cadaveric kidneys.