This article reviews methodological issues around screening for hepatocellular carcinoma, and discusses selection of the at-risk group, which screening test to use, and how frequently it should be applied. Screening of patients at risk for hepatocellular carcinoma should be undertaken using ultrasonography applied at six-month intervals. Patients at risk include all those with cirrhosis, and certain non-cirrhotic patients withchronic hepatitis B. In this population, screening has been shown to reduce disease-specific mortality. Although data do not exist for other populations, screening is nonetheless advised because small cancers can be cured with appreciable frequency.