To investigate the infectivity for hepatitis C virus (HCV) of intravenous anti–D immunoglobulin batches manufactured in Ireland between 1991 and 1994. Women who had received anti–D manufactured between 1991 and 1994 were screened for serological markers of HCV infection and for the presence of HCV RNA by RT–PCR amplification and virus genotyping. 44 women exposed to anti–D manufactured between 1991 and 1994 were polymerase chain reaction positive for HCV RNA, 19 of whom were infected with genotype 3a virus shown by phylogenetic analysis of the NS5B gene to be closely related to that from the single implicated donor. Anti–D manufactured in 1991–1994 transmitted infection of HCV genotype 3a. The prevalence of HCV–specific antibody in anti–D recipients was relatively low (0.59%), consistent with the low level of virus RNA in these anti–D batches.