In the Research Letter entitled “Comparing Newer GFR Estimating Equations Using Creatinine and Cystatin C to the CKD-EPI Equation in Adults” that appeared in the October 2017 issue of AJKD (Levey et al, volume 70, issue 4, pages 587-589), there was an error in the number of participants given for the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine validation database. As discussed in a 2011 correction in Annals of Internal Medicine (https://dx.doi.org/10.7326/0003-4819-155-6-201109200-00024), the number of participants is 3,771, not 3,896.