We prospectively assessed the value of estimated glomerular filtration rate (eGFR) by the Modification of Diet in Renal Disease (MDRD) and Cockcroft-Gault (C-G) equations in predicting inhospital adverse outcomes after primary coronary intervention for acute ST-segment elevation myocardial infarction. We classified 647 patients into 3 categories according to eGFR, <60, 60 to 90, and >90 mL/min/1.73 m(2). The eGFRC-G classified 17 patients in the >90 mL/min/1.73 m(2) subgroup and 6 and 11 patients in the 60 to 90 and <60 mL/min/1.73 m(2) subgroups, respectively. In multivariate analysis, patients with eGFRC-G <60 mL/min/1.73 m(2) had 19.5-fold (95% confidence interval [CI] 1.55-178) higher mortality risk and 5.48-fold (95% CI 1.75-24.21) higher major adverse cardiac events risk compared to patients with eGFRC-G >90 mL/min/1.73 m(2) (P = .01 and P = .01, respectively); the eGFR(MDRD) was not predictive. Although the MDRD equation more accurately estimates GFR in certain populations, the CG formula may be a better predictor of adverse events.