In a study designed to assess the prevalence of antibodies to hepatitis C virus (HCV) in pregnant women, anti-HCV positivity in French pregnant women was twice as high as that found in French blood donors. Positive ELISA 2 results were confirmed by positive RIBA 2 in most subjects, and seven of nine RIBA 2 positive patients also tested positive for HCV-RNA by PCR. High rates of anti-HCV positivity were seen among immigrant pregnant women, partly because of false positive results with ELISA 2. RIBA 2 results suggested that the prevalence of HCV infection was not any higher in immigrant compared with French pregnant women.