The waiting list for liver transplantation has more than doubled between 1988 and 1992, yet the number of liver transplantations during the same period increased by only 79%. This discrepancy is due to the limited availability of donors. The modest increase in donor pool is caused entirely by donors > or = 40 years of age, a trend likely to continue. To determine the impact of increasing donor age on the outcome of liver transplantation, we analyzed 6-month graft survival in 7,988 adults who received first liver graft between October 1987 and September 1992, and were observed through the United Network for Organ Sharing Scientific Liver Transplant Registry. Graft survival was measured by death and/or retransplantation, donor age by decades. The independent effect of donor age on graft survival was estimated by Cox regression analysis controlling for the possible confounding of donor, recipient, and institutional characteristics. Between 1987 and 1992, the percentage of donors over 50 years increased from 2.1% to 17.5% resulting in change of median donor age from 23 to 31 years. For donor age > or = 50, graft failure rate was 50% higher than with donor age less than 20 years (excess for mortality was 25% and for retransplantation 94%). Adjustment for characteristics associated to donor age or outcome did not eliminate the excess risk found with increasing donor age. Despite these adversities, graft failure rate in recipients from oldest donors (27.2%) in 1992 was nearly equivalent to recipients from the youngest donors (26.9%) in 1987 to 1988. Although increasing donor age has an adverse effect on 6-month graft survival, improvement in transplantation technology and patient care over time have more than compensated for poorer graft function associated with the simultaneous rise in median donor age.