['An estimated 3.2 million persons are chronically infected with the hepatitis C virus (HCV) in the U.S. Effective treatment is available, but approximately 50% of patients are not aware that they are infected. Optimal testing strategies have not been described.', 'The Hepatitis C Assessment and Testing Project (HepCAT) was a serial cross-sectional evaluation of two community-based interventions designed to increase HCV testing in urban primary care clinics in comparison with a baseline period. The first intervention (risk-based screener) prompted physicians to order HCV tests based on the presence of HCV-related risks. The second intervention (birth cohort) prompted physicians to order HCV tests on all patients born within a high-prevalence birth cohort (1945-1964). The study was conducted at three primary care clinics in the Bronx, New York.', 'Both interventions were associated with an increased proportion of patients tested for HCV from 6.0% at baseline to 13.1% during the risk-based screener period (P<0.001) and 9.9% during the birth cohort period (P<0.001).'] Are primary care-based interventions associated with increases in hepatitis C virus testing for patients at risk?