Creatinine clearance is by far the most frequently used index to evaluate the GFR in clinics. Ever since Schwartz reported the formula for the calculation of the creatinine clearance there had been many other reports on other formulas but mostly not popularly used. As Schwartzs formula is derived on the presumption that height has the best represention of muscle mass, we have searched for other anthropometries which could represent the creatinine clearance. Also other than the Ghazall and Barratts formula which was to determine whether the 24 hour urine collected had accurate sample, we tried to deduct a relation between the anthropometries and 24 hour urine creatinine which could tell us whether we had collected accurate sampling of urine. Results .' 1) The first class sample (1 month old or less infant) showed C, (ml/min/1.73 m)=5.87xRohler index/P +4.4 (r=0.85) and U(mg/day)=14.63xRohler index 5.64 (r=0.52). 2) The second class sample (1 month old-2 year old) showed C, (ml/min/1.73 m)=1.66x Weight/P <,+18 (r =0.7) and U <, (mg/day)=18.83x Weight 68 (r=0.63). 3) The third class (2 year old-15) showed C <, (ml/min/ 1.73 m)=0.49xLength