Abstract： Objective To study the prenatal genetic diagnostic methods for hemophilia A fetus.Methods From 2002 to 2006,19 hemophilia A families were diagnosed either by long distance-polymerase chain reaction(LD-PCR)for factor Ⅷ intron 22 inversion or by the DNA polymorphism genetic linkage analysis of factorⅧin the Beijing Chaoyang Hospital.Results (1)Totally 19 women,with 22pregnancies received the prenatal diagnosis of fetal hemophilia A.The average week at diagnosis was 23(17-34)weeks.All the direct fetal blood sampling(DFBS)were successful.There was no fetal-loss caused by the procedures.(2)Of the 19 hemophilia A families,14 appeared to be factorⅧintron 22inversion,in which 16 prenatal diagnoses were done,10 fetuses were diagnosed as genetical hemophilia A patients,and 6 fetuses were normal.(3)Using combined polymorphism genetic linkage analysis 6 prenatal diagnoses were done,including one woman's two pregnancies,in which both her fetuses were diagnosed as genetical hemophilia A patients.(4)Factor Ⅷ levels of 16 fetuses were measured,and 6 fetuses were unmeasured either because the pregnancy weeks were lower than 20 weeks or the parents refused.Factor Ⅷlevel ranged from 0 to 198%.There were 11 fetuses whose factor Ⅷ levels were lower than 10%.Ten of them were diagnosed to be genetical hemophilia A patients,and in only one boy the factorⅧlevel was 2%,but the genetic diagnosis was normal and for one year's follow up he was doing normal.Conclusion LDPCR combined with polymorphism genetic linkage analysis enables a quick and correct detection ofhemophilia A carrier.For a carrier pregnancy.prenatal diagnosis could be done for the male fetus.Factor Ⅷ deficiency of the fetus could help make the diagnosis but the final diagnosis should be based on genetic evidence.