Perinatal transmission of Hepatitis B virus from mother to their child is main route of the infection in Vietnam. Vaccination is the most important preventive meassure to decrease the rate of HBV infection in public. The first period,authorsresearch some HBV markers in umbilical cord blood from child and in mother blood in Bach Mai hospital. The results showed that HBsAg (+) rate from umbilical cord blood of offspring born to mothers with HBsAg( +) is 61,3 percent. All infants with HBsAg( -) were offspring of mothers who were HBeAg ( -). However, HBeAg marker might be positive in umbilical cord blood of off spring not only born to mothers with HBeAg (+) but also to thoc
p with HBeAg (-).