The purpose of this study was to investigate the time course of contrast enhancement in bile ducts and the gallbladder (GB) after injection of gadolinium-ethoxybenzyl-DTPA (Gd-EOB-DTPA). In a clinical phase-I study, MR imaging at 1.5T was performed in 16 healthy volunteers with four different doses of Gd-EOB-DTPA (10, 25, 50, and 100 micro;mol/kg b. w., four volunteers per dosage). The study protocol comprised a heavily T1-weighted fast multiplanar gradient-echo (GE) sequence before and at increasing intervals for up to 360 min after injection of Gd-EOB-DTPA. The signal enhancement was evaluated in extra- and intrahepatic bile ducts as well as in the GB. In all 16 volunteers the common bile duct showed intense signal enhancement beginning 5-16 min after injection (mean 10 min) and persisting for at least 120 min in 4 subjects and for 360 min in 12 subjects. The duration of signal enhancement was significantly (p < 0.05) longer for higher doses (50, 100 micro;mol/kg) than for lower doses (10, 25 micro;mol/kg). Intrahepatic bile ducts were hyperintense as compared with liver parenchyma in all subjects receiving 10 micro;mol/kg from approximately 50-120 min after contrast agent application. Intrahepatic bile ducts were not displayed using the higher doses, probably because of the strong enhancement of the liver parenchyma. Gallbladder contrasting was achieved in all cases beginning 7-33 min after injection (mean 19 min) and remained visible for up to 360 min in 94 %. Hyperintense visualization of normal extrahepatic bile ducts as well as the GB is regularly achieved with the hepatobiliary contrast agent Gd-EOB-DTPA. The dosage for hyperintense visualization of intrahepatic bile ducts is 10 micromol/kg.