Total bile acid concentration was determined in systemic and portal serum and in liver tissue from patients with presumably normal liver function, and from patients with extrahepatic cholestasis. Systemic and portal serum bile acids were also determined in patients with alcoholic liver cirrhosis. In 5 patients, in whom a portal catheter was inserted through the umbilical vein, the diurnal variation in systemic and portal serum bile acid concentration was studied. In patients with presumably normal liver function the fasting systemic serum bile acid concentration was 4.8+/-0.5 mumol times 1(-1), and the portal concentration was 12.9+/-1.5 mumol times 1(-1). In cholestasis and liver cirrhosis the systemic and portal bile acid concentration was substantially elevated. The bile acid concentration gradient between systemic serum, portal serum, liver tissue, and hepatic bile was 1:3:80:2600 in the patients with normal liver function. In both the cholestatic and cirrhotic condition the systemic and portal serum bile acid concentration was equilibrated. Postprandially both the systemic and portal bile acid concentration increased, but the gradient between these concentrations was unchanged. The results are compatible with the hypothesis that portal and systemic serum bile acid concentrations are determined by the intestinal absorption rate in subjects with normal liver function and by the hepatic and renal clearance capacity in cholestatic and cirrhotic conditions.