99mTc diethylenetriaminepentaacetic acid (stannous) is cleared from the blood by glomerular filtration. However, calculation of the glomerular filtration rate has required analysis of serial blood samples drawn over intervals of several hours in order to determine the radionuclide clearance rate. This lengthy procedure can be circumvented by the direct scintigraphic determination of fractional radionuclide accumulation within each kidney, occurring at a specified time interval after radionuclide administration. This value has been correlated with 24 hr creatinine clearance values in a group of hospitalized patients. From these data, a formula was derived allowing for estimation of total glomerular filtration rate, as well as individually for each kidney, without requiring blood samples. This procedure needs only 6 min of patient time.