131I labelled Rose Bengal is offered as an aid for estimating the functional state of the liver, gall bladder and patency of the biliary tree. When the tracer is injected intravenously, it is cleared from the blood by the polygonal cells of the liver, excreted into the bowel and discharged into the duodenum. The equipment used was a gamma camera and small digital image processing system with area of interest capability. The diagnostic criteria used were those of blood retention, maximum hepatic uptake, liver, gall bladder and biliary tree visualisation times and time of excretion into the duodenum. Preliminary results from the findings in 60 patients of whom 42 were jaundiced are presented to demonstrate the ability of the technique to disclose evidence indicating intra- or extrahepatic causes of jaudice. Of 33 patients with proven extrahepatic obstruction Rose Bengal scanning provided the correct evidence in 31 cases, the other two having intermittent obstruction by common bile duct stones. Of the 12 patients with proven diffuse parenchymal disease the technique disclosed the correct evidence in all cases. All four post-cholecystectomy patients with recurrence of symptoms showed good visualisation of the duct system and excretion into the bowel.