The cytomegalovirus infection is most common causes of intrauterine infection of the fetus. Using of serologic diagnostic methods the kind of infection is unknown. The aim of the study was assessment of the risk of CMV infection depending of genome account in mother's blood and I amniotic fluid. The study was performed in choosen pregnancies, in which we expected cytomegalovirus infection using serological criteria. In prenatal diagnostic CMV infection using QPCR, the best material is amniotic fluid. Mother's blood assessment of CMV genome count does not make growth diagnostic possibility of the assesement of transmission the infection from mother to fetus.