This study was designed to determine the seroprevalence and risk factors for hepatitis C virus (HCV) infection in veterans. Anti-HCV testing was performed in 1,032 patients and a questionnaire regarding sociodemographic characteristics and potential risk factors was administered. Adjusted prevalence of unique HCV-positive patients using outpatient services was 17.7% (95% confidence interval [CI] 17.2%, 18.2%). The following risk factors were associated with HCV infection: a history of injection drug use (IDU), receipt of blood transfusion prior to 1992, history of tattoo (odds ratio [OR], 2.93; 95% CI, 1.70-5.08), combat job as a medical worker (OR, 2.68; 95% CI, 1.25-5.60), history of incarceration over 48 hours (OR, 2.56; 95% CI, 1.52-4.32), greater than 15 lifetime sexual partners (OR, 1.61; 95% CI, 0.94-2.76) and sexual relations with a prostitute (OR, 0.46; 95% CI, 0.25-0.82). We concluded that HCV is common in veterans. Risk factors independently associated with infection are IDU, prior transfusion, prior tattoo, combat medical work, incarceration, and multiple opposite sex partners. Infection with HCV among veterans is strongly associated with traditional risk factors for infection and less strongly associated with combat-related risk.