Ultrasound examination was performed in 53 jaundiced patients; successful examination was accomplished in 48. Ultrasonography revealed mechanical biliary obstruction in 34 of 35 patients with obstructive jaundice. Dilatation of the intrahepatic or extrahepatic biliary ducts or the gallbladder was not present in any patient with non-obstructive jaundice. The value of ultrasound examination in the differential diagnosis of jaundice is emphasized.