To monitor the prevalence of hepatitis B and hepatitis C a cross-sectional survey was conducted in 2004 among French metropolitan residents. A complex sampling design was used to enroll 14,416 adult participants aged 18–80 years. Data collected included demographic and social characteristics and risk factors. Sera were tested for anti-HCV, HCV-RNA, anti-HBc and HBsAg. Data were analyzed with SUDAAN® software to provide weighted estimates for the French metropolitan resident population. The overall anti-HCV prevalence was 0.84% (95% CI: 0.65–1.10). Among anti-HCV positive individuals, 57.4% (95% CI: 43.2–70.5) knew their status. Factors associated independently with positive anti-HCV were drug use (intravenous and nasal), blood transfusion before 1992, a history of tattoos, low socioeconomic status, being born in a country where anti-HCV prevalence >2.5%, and age >29 years. The overall anti-HBc prevalence was 7.3% (95%: 6.5–8.2). Independent risk factors for anti-HBc were intravenous drug use, being a man who has sex with men, low socioeconomic status, a stay in a psychiatric facility or facility for the mentally disabled, <12 years of education, being born in a country where HBsAg prevalence >2%, age >29 and male sex. The HCV RNA and HBsAg prevalence were 0.53% (95% CI: 0.40–0.70) and 0.65% (95% CI: 0.45–0.93), respectively. Among HBsAg positive individuals, 44.8% (95% CI: 22.8–69.1) knew their status. Anti-HCV prevalence was close to the 1990s estimates whereas HBsAg prevalence estimate was greater than expected. Screening of hepatitis B and C should be strengthened and should account for social vulnerability. J. Med. Virol. 82:546–555, 2010. © 2010 Wiley-Liss, Inc.