In order to assess the clinical value of 99Tcm-HIDA for hepatobiliary scintigraphy 23 patients with hepatocellular disease and 44 patients with obstructive biliary tract disease were examined. Positive information was obtained in 14 and 23 patients, respectively. False results mainly depended on inadequate imaging of the liver in the case of severely impaired function, whatever the cause. Spontaneously ameliorated obstruction leaving an impaired hepatocellular function may give misleading results. A malignant tumour widely involving the liver and impressing the bile ducts may also create the appearance of obstruction. If HIDA scintigraphy be limited to patients with serum bilirubin levels between 40 and 250 mumol/l the diagnostic specificity and sensitivity of 90 per cent and 78 per cent, respectively, is reached in demonstrating obstruction, when the prevalence is 0.58.