Bile acids are increasingly used as test substances for the estimation of liver function and it has been postulated that radioactive labeled bile acids have advantages over indocyanine green (ICG) for measurement of hepatic blood flow. Therefore, the hepatic extractions of 14C-taurocholate and ICG were compared in 23 patients with liver disease and correlated with various parameters of hepatic function. The hepatic extractions of 14C-taurocholate (mean: 42 +/- SD 17%) and ICG (mean: 35 +/- SD 18%) were similar. The correlations with galactose elimination capacity and BSP plasma disappearance were closer for ICG than for 14C-taurocholate extraction. Hepatic blood flow measured with 14C-taurocholate (mean: 1.45 +/- SD 0.51 l/min) correlated well (r = 0.81) with the respective values obtained with ICG (mean: 1.17 +/- SD 0.49 l/min), but was about 22% larger. This study does not provide evidence that 14C-taurocholate is superior to ICG as an intravenous test substance for measurement of hepatic function or blood flow.