The non-invasive diagnostic technique of computed tomograph (CT) has been assessed in 100 patients with established liver disease. CT can differentiate extra- from intrahepatic cholestasis and may define the obstructing lesion in the former group. It is of value in detecting infiltrations with fat or iron, and provides useful information in patients with cirrhosis and metastatic deposits. At present it appears of less value in the diagnosis of non-fibrotic parenchymal liver disease.