1. The disposition of an intravenous bolus of indocyanine green (ICG) has been studied in healthy man and baboons using a novel analysis of a two compartment pharmacokinetic model.
2. This analysis enabled the hepatic extraction ratio (ER) of dye to be determined solely from the plasma disappearance curve, and the ER determined did not differ from that measured by hepatic vein catheterization.
3. When compared with clearance measured at steady state, the two compartment model gave a significantly more accurate determination of plasma clearance than did the conventional one compartment model.
4. It is concluded that, in health, liver blood flow may be calculated accurately and noninvasively after a single intravenous injection of ICG.