Five-year follow up was completed in November 2007. The 5-year cumulative probability of success was 86%: 86% in the <66.0 year donor age group and 86% in the >=66.0 year donor age group (difference = 0%, upper limit of one-sided 95% confidence interval = 4%). Adjusting for baseline endothelial cell density had no appreciable effect on these results. In a statistical model with donor age as a continuous variable, there was not a significant relationship between donor age and outcome (P=0.11). Three graft failures were due to primary donor failure, 8 to uncorrectable refractive error, 48 to graft rejection, 46 to endothelial decompensation, and 30 to other causes. At least one probable or definite graft rejection episode preceded graft failure in 23 of the 46 failures attributed to endothelial decompensation (4 definite and 19 probable) and in 18 of the 30 failures attributed to other causes (4 definite and 14 probable). The distribution of causes of failure between the donor age groups did not substantially differ.