Measurement of the glomerular filtration rate (GFR) is an essential element in assessing renal function. Formulaic estimations of GFR (eGFRs) are widely used but have many pitfalls. Application of eGFR without adjustment for the effects of aging and gender results in overdiagnosis of chronic kidney disease (CKD). eGFR formulae also contain variables that independently influence the risk of CKD and cardiovascular disease. eGFR needs a performance review to foster its evolution as a clinically useful tool.