The article presents the development and validation of a new equation, the CKD-EPI creatinine equation, for estimating glomerular filtration rate (GFR) in adults. The equation was designed to improve upon the limitations of the widely used MDRD Study equation, particularly in estimating GFR at higher levels. The CKD-EPI equation incorporates a spline term for serum creatinine, which allows for a steeper relationship between creatinine and GFR at higher levels, reducing bias. The equation was developed using data from 10 studies (8,254 participants) and validated in 16 studies (3,896 participants). In the validation dataset, the CKD-EPI equation showed better performance than the MDRD Study equation, with lower bias, improved precision, and greater accuracy, especially at higher GFR levels. The CKD-EPI equation also led to a lower estimated prevalence of chronic kidney disease (CKD) compared to the MDRD Study equation, primarily due to a lower prevalence of Stage 3 CKD. The article concludes that the CKD-EPI equation is more accurate and could replace the MDRD Study equation for routine clinical use, with potential implications for public health and clinical decision-making.The article presents the development and validation of a new equation, the CKD-EPI creatinine equation, for estimating glomerular filtration rate (GFR) in adults. The equation was designed to improve upon the limitations of the widely used MDRD Study equation, particularly in estimating GFR at higher levels. The CKD-EPI equation incorporates a spline term for serum creatinine, which allows for a steeper relationship between creatinine and GFR at higher levels, reducing bias. The equation was developed using data from 10 studies (8,254 participants) and validated in 16 studies (3,896 participants). In the validation dataset, the CKD-EPI equation showed better performance than the MDRD Study equation, with lower bias, improved precision, and greater accuracy, especially at higher GFR levels. The CKD-EPI equation also led to a lower estimated prevalence of chronic kidney disease (CKD) compared to the MDRD Study equation, primarily due to a lower prevalence of Stage 3 CKD. The article concludes that the CKD-EPI equation is more accurate and could replace the MDRD Study equation for routine clinical use, with potential implications for public health and clinical decision-making.