Abstract: Angiographic visualization of the hepatic vascular bed by selective angiography can be profitably complemented with the evaluation of functional portal-systemic shunting by D-sorbitol bioavailability. Seventeen patients requiring diagnostic arterial catheterization were studied: most of them had biopsy-proven liver cirrhosis. Patients were studied at rest and after overnight fasting on two subsequent days, in which a sterile pyrogen-free solution (1.5%) of D-sorbitol was administered by direct infusion (15 mg/min for 20 min) into the superior mesenteric artery and an antecubital vein, respectively. The fractional bioavailability (Fma) of Dsorbitol was calculated as the ratio between the net cumulative urinary outputs obtained after infusion through the catheter into the superior mesenteric artery and the systemic vein, respectively. A good correlation was found between the estimated fractional portal-systemic shunting, which in the present study ranged between 1.4% and 96.7%, and a suitable index scoring the clinical evidence of collateral circulation. Since the hepatic removal of D-sorbitol is not affected by sinusoidal capillarization and its hepatic extraction ratio is quite high and only slightly modified by reduction in the number or functional activity of hepatocytes, the measured Fma can be assumed as a parameter reflecting the entity of portal-systemic shunting. The test is safe and inexpensive, and appears potentially useful in several situations in which portal-systemic shunting is pathophysiologically relevant.