A nuclear medicine procedure that has been used for quantification of hepatocyte function in man is applied and validated in the dog. This procedure employs deconvolutional analysis of liver and heart time activity curves obtained following peripheral intravenous injection of hepatobiliary radiopharmaceutical. The deconvolutional analysis simulates a bolus injection of the radiopharmaceutical into the afferent blood supple of the liver which permits the calculation of the hepatic extraction fraction. Hepatic extraction fraction is a measure of hepatocyte function. In this report, the deconvolutional analysis via fast Fourier transformations and subsequent calculation of hepatic extraction fraction is validated by direct afferent intravascular ijection of 99mTc-mebrofenin. The hepatic extraction fraction determined via deconvolutional analysis was found to be the same as the first pass hepatic extraction fraction determined via deconvolutional analysis was found to be the same as the first pass hepatic extraction fraction determined by direct mesenteric (portal) vein injection. The same results can be obtained in a sedated animal, making the technique clinically applicable. Thus hepatic extraction fraction, obtained from a perlpheral intravenous injection of 99mTc-mebrofenin, can provide a quatitative measure of hepatocyte function from a non-invasive procedure. The quantitative ability to measure hepatocyte function has potential in many clinical and research situations.