In past decades, several experiments reported there presences of integrated HBV DNA in human spermatozoal chromosomes. Studies on embryos hybridized with mammalian ova and human spermatozoa were also confirmed that sperm-integrated HBV DNA can replicate and express the HBV protein in two-cell' hybrid embryos. All above findings demonstrated that father might transmit HBV to fetus by spermatozoa in theory.