In the Original Investigation entitled “Serum β-Trace Protein and β2-Microglobulin as Predictors of ESRD, Mortality, and Cardiovascular Disease in Adults With CKD in the Chronic Renal Insufficiency Cohort (CRIC) Study” that appeared in the July 2016 issue of AJKD,1 there was an error regarding the source of the β-Trace Protein (BTP) and β2-Microglobulin (B2M) samples. The samples were reported as being measured in serum; however, the samples were measured in EDTA plasma.