The eGFR equation from the Modification of Diet in Renal Disease (MDRD) study has been used worthwide and automatic reported the result of eGFR with serum créatinine through the internet working network Objective: To select the best equation among 3 eGFR equations as 1) MDRD equation, 2) MDRD equation modified from Japan; 3) CKD-EPI equation, compared with 24h creatinine clearance, and the estimated creatinine clearance (eClcre) by Cockcroft Gault formula. Method: prospective, cross sectional study. Results: We had 504 participants (101 healthy volunteers, 403 chronic kidney disease patients; 237 males, 247 females) with 867 times serum créatinine and Clcre24h measurement.