Classic hemophilia, (hemophilia A), is an X-linked hereditary bleeding disorder affecting half of the male offspring of female carriers. Prenatal diagnosis offers an option, namely to restrict abortions to hemophilic fetuses only, and thus retain the chance of bearing normal sons. Recently, the authors have made a prenatal diagnosis of hemophilia A in an obligate carrier with a male fetus at 24 weeks of gestation by pure fetal sampling and accurate factor VIII coagulant assay, which was repeatedly less than 1% at 28 weeks of gestation.