Many previously described nuclear medicine procedures to assess glomerular filtration rate (GFR) required numerous blood samples obtained over a period of several hours to determine plasma concentrations of the injected radiopharmaceuticals. And other indirect methods of determining renal clearance have some problems due to individual variations in volume of distribution of the radionuclides used. Rescently reported Jackson's method have the great advantages that is a direct measurement method requiring less than 40 min of imaging time and single blood sampling. And it correctly accounts for individual variations in volume of distribution of the radiopharmaceuticals and can be done with routine renal scintigraphy. We measured Tc- 99m-DTPA renal clearance with Jackson's method during the routine Tc-99m-DTPA renal scintigraphy in 63 patients admitted to department of internal medicine in SNUH. In 23 cases among 63 patients creatinine clearence was accounted simultaneously. The range of ClDPDA was from 19.9 ml/min to 170 mi/min and the correlation of ClDPDA and creatinine clearance was discribed by Y=16.2570+0.7852X(X=C1DPDA, Y=creatinine clearance). And the correlation coefficient r was 0.88. We concluded that Tc-99m-DTPA renal clearance measurement with Jackson's method was clinically useful to account GFR that can be done with routine Tc-99m-DTPA renal scintigraphy simultaneously.