ades ago. Donors older than 60 years are currently Introduction accepted in living related [3] and in cadaveric [4] transplantation. Advanced donor age is associated with The permanent shortage of organs has led to attempts graft survival rates reduced by approximately 20–30% to expand the donor pool. Identifying which kidneys at 3 or 5 years after transplantation, and with subpreviously considered suboptimal can be safely optimal renal function [3–5]. According to the Catalan accepted for transplantation may help to reduce the Registry [1], only 20% of recipients of renal allografts number of patients on waiting lists. On the other hand, from donors older than 60 years have a calculated changes in demographic characteristics of developed creatinine clearance higher than 59 ml/min; in contrast, countries, with an increasing ageing population, makes 50% of patients have such a creatinine clearance when it more necessary to review donor acceptance criteria transplanted with organs from donors younger than to maintain acceptable results even in current trans30 years. plant activity. In Catalonia in 1990 the proportion of Ageing and hypertension may be associated with donors older than 50 years was 17%; this had increased pre-existing lesions that entail a poor renal function to 45% in 1997. During the same period the mean and graft outcome. Considering the limited value of donor age rose from 31.4 years to 45.6 years. Moreover, serum creatinine for assessing renal function immedithe proportion of donors dying from cerebrovascular ately before harvesting, renal biopsy is the most useful accident, which was less than 40% in 1990, rose to tool for evaluating the viability of a kidney for transover 50% in 1997 [1]. Similar data have been reported plantation. Renal damage assessed with a semiquantitby the United Network for Organ Sharing in the ative scale or with a quantitative parameter such as United States [2]. the percentage of sclerosed glomeruli or the expansion The increasing proportion of suboptimal, marginal, of the interstitial space, correlates with the incidence or borderline donors raises several questions. The most of post-transplant delayed graft function and renal important issues regarding these donors are the followfunction [6–8]. Twenty per cent glomerulosclerosis is ing: (i) definition of marginal or borderline donors; usually considered the upper limit for accepting kidneys (ii) acceptance criteria; (iii) techniques of organ preserfrom a marginal donor [4]. However, a more complex vation for kidneys harvested from these donors to score, including glomerular, tubular, interstitial, and minimize the incidence of delayed graft function; (iv) vascular lesions, may better reflect the viability of allocation of such organs, which may be related to the kidneys for transplantation. Such an index has been nephron mass provided to the recipient; (v) immunoused to select kidneys for single and double renal suppression regimens to prevent rejection and reduce transplantation [9]. nephrotoxicity; and (vi) the expected graft and patient outcomes.