This systematic review addresses the following questions: (1) What is the efficacy of using screening tests for hepatocellular carcinoma (HCC) in improving outcomes in chronic hepatitis C, and (2) what are the sensitivity and specificity of screening tests for HCC in chronic hepatitis C? The search strategy involved searching Medline and other electronic databases between January 1985 and March 2002. Additional articles were identified by reviewing pertinent articles and journals and by querying experts. Articles were eligible for review if they reported original human data from studies of screening tests that used virological, histological, pathologic, or clinical outcome measures. Data collection involved paired reviewers who assessed the quality of each study and abstracted data. One nonrandomized prospective cohort study suggested that HCC was detected earlier and was more often resectable in patients who had twice yearly screening with serum alpha-fetoprotein (AFP) and hepatic ultrasound than in patients who had usual care. Twenty-four studies, which included patients with chronic hepatitis C or B or both, addressed the sensitivities and specificities of screening tests. They were relatively consistent in showing that the sensitivity of serum AFP for detecting HCC usually was moderately high at 45% to 100%, with a specificity of 70% to 95%, for a threshold of between 10 and 19 ng/mL. The few studies that evaluated screening with ultrasound reported high specificity, but variable sensitivity. In conclusion, screening of patients with chronic hepatitis C with AFP and ultrasound may improve detection of HCC, but studies are needed to determine whether screening improves clinical outcomes.