The accuracy of ultrasonography in detecting the right hepatic artery was prospectively assessed in 128 patients undergoing abdominal angiography. Twenty-five (19%) of the ultrasound studies were technically inadequate mainly because of gas superimposition. Of the remaining 103 cases, 14 had a replaced hepatic artery, which was diagnosed in 10 cases with ultrasound (sensitivity 71%). Eighty-nine did not have a replaced hepatic artery and the ultrasound assessment was falsely positive in four of them (specificity 96%). Two of the four false negative results could be explained by a stenosis of the superior mesenteric artery in front of the origin of the replaced hepatic artery. Two of the four false positive results could be explained by the presence of a stenosis of the celiac trunk with hypertrophy of the pancreaticoduodenal arteries, one of them being misdiagnosed as a replaced hepatic artery.