Since the immune response in older recipients is weaker they should be less likely to reject a transplanted organ and should need less aggressive immunosuppressive treatment. Our aim was to record the incidence and severity of episodes of acute rejection (AR), estimate the influence of these events on graft survival of elderly recipients (> or = 60) and to compare these with that in younger ones. We performed 363 kidney transplants between 1/94 and 12/98, and recorded clinical and immunological data, incidence-severity of AR and cause of graft loss. Patients were divided into two groups, according to the age at transplantation: A (<60, n = 281/77.4%) and B (> 60, n = 82/22.6%). The percentage of aging recipients and mean age of donors and recipients increased throughout the period. Although the incidence of ATN was higher in the older group (29% vs.19%, p < 0.0001) the number of graft biopsies was equal in both groups. The incidence of AR was similar, 33.4% vs. 26.8%, pNS. The number of AR episodes per patient was 0.44 and 0.41 respectively. The severity of AR was: Banff grade I: A (40.3%)/B (45.7%) pNS; grade II: A (44.1%)/B (48.57) pNS; grade III: A (15.5%)/B (5.7%) pNS. Younger recipients presented a higher level of panel-reactive antibodies (PRA) (4.3% vs. 2.07%, p = 0.01). One-yearpatient survival was 96%/91% (p < 0.05) and graft survival was 81%/78% (pNS) respectively. The age of recipient does not seem to have influenced the incidence-severity of AR or the graft survival. Thus immunosuppression should be individualized for each patient and should not depend on the age at transplantation.