A dults who are aged 25 to 30 y at the time of kidney donation will likely live another 50 y, making their lifetime risks of end-stage renal disease (ESRD) difficult to characterize. Massie et al 1 recently reported a 1.5% 30-y cumulative ESRD risk for US donors in the Organ Procurement and Transplantation Network database. He confirmed risks at 10 and 20 y, 1-3 which were <1.5% but were increasing exponentially, as they do in the general population. 4,5 Most transplant professionals currently believe that postdonation ESRD risks are less than-or at worst no greater than-population risks. 6,7 This was suggested by early 10-y studies showing that ESRD rates in donors were lower than average rates in the general population. 8,9 Average population rates were calculated by dividing the yearly incidence of ESRD by the population census-about 113 000 of 310 000 000 or 0.037%/y (0.37%/decade). If ESRD accumulated linearly-not exponentially-in donors and in the general population (ie, if the 30-y risk was 30 times the 1-y risk), donor risk would always be lower than population risk. The same analysis was applied to relatively increased postdonation risks in Black donors, 8 who have increased risks in the general population as well. 4,5 However, when ESRD rates in donors are compared with those in the general population, their exponential increases must be considered. Data by Massie et al help make this possible.ESRD in the US general population is well characterized. 4,5 It is as rare in 25-y-olds as it is in the first 10 y after kidney donation. New onset ESRD increases exponentially from about 60/million/y at age 25 to almost 1500/ million/y by age 80. 5 Lifetime ESRD risks are the sums of yearly risks from birth to age 78 to 80, an average lifespan. 4,5,10 Lifetime risks are gradually increasing for decades and now approach 3.5%, with 7.5% for the Black Expert Insight