The fractional renal uptake of intravenously administered Tc–99m DTPA, within 2 to 3 minutes following radiotracer arrival in the kidneys, is proportional to the glomerular filtration rate (GFR). Thus it is possible to determine total, as well as individual kidney, GFR by a radionuclide technique which needs only six minutes of patient time and requires neither blood nor urine samples. The radionuclide computed GFR correlates extremely well with 24–hour creatinine clearance determinations, and is highly reproducible. This method has been used in nearly 500 split renal function determinations and has provided valuable, accurate information.