Quantitation of renal function may be performed with a variety of radiopharmaceuticals which reflect slightly different renal functions. Plasma sampling techniques and imaging techniques have been used to derive absolute measurements of renal function. The addition of imaging permits the determination of relative or "split" function. Time-activity curves from renal studies provide other quantitative parameters of function reflecting arterial supply, renal cortical function, and patency of the renal collecting system. Quantitative radionuclide studies of the kidneys provide comprehensive, reproducible, and objective assessments of renal function.