The early identification of chronic kidney disease (CKD) is a legitimate enterprise if it provides meaningful opportunities for effective and safe interventions that reduce the risk of death, end-stage renal disease, or complications of renal dysfunction. The screening of unselected populations not already known to be at risk of CKD has the potential of harm and has not been shown to be cost-effective. The application of formulas for the estimation of GFR (eGFR) to the guidelines for staging of chronic kidney disease (Kidney Disease Outcomes Quality Initiative, K/DOQI) as universal screening tools is of dubious value and has inherent dangers. This conclusion is based both on the unreliability of current formulas for determining eGFR and flaws in the K/DOQI schema for staging of CKD. The failure to take into account the normal age- and gender- associated decline in GFR and the lack of a requirement for other evidence of kidney disease in CKD stage 3 leads to an erroneous categorization of large numbers of mostly elderly and female subjects as having an intermediate stage of a lethal disease. Criteria for CKD staging should take into account the percentile distribution of eGFR by age and gender. Targeted screening for CKD is likely to be more cost-effective than universal screening. Whether early identification and treatment of subjects with "reduced" levels of GFR within the normal range for their age/gender, but without any other manifestations of kidney disease, will reduce the subsequent risk of cardiovascular events or progression to end-stage-renal disease is currently unproven.