There is a lack of knowledge of the placental abnormalities of congenital herpesvirus infection. The presence of chorioamnionitis is morphologic evidence that this congenital infection is characteristically acquired by ascent of the virus from a resident location within the maternal cervix. A unilateral emigration of placental plasma cells from superficial fetal vessels to the placental surface may represent a heretofore undescribed occurrence of plasma cell participation in chemotaxis.