The relation between systemic hepatic clearance, intrinsic hepatic clearance and hepatic blood fow is considered from the point of view of the sinusoidal perfusion (parallel tube) model of the liver. 2. It is shown how intrinsic hepatic clearance may be calculated, for substrates eliminated in the liver and the kidney only, from data obtained by introducing successively an oral and an intravenous dose (i.e., by using the first-pass effect) with the clinically cumbersome catheterization of the liver vein. 3. The rate of hepatic blood flow is shown to follow from the same data.
