Neonatal herpes simplex virus (HSV) infections are frequently characterized by widespread dissemination and high morbidity and mortality. To assess the potential role of the lymphocyte in permitting or promoting dissemination of HSV, we studied lymphoid populations of placental and adult blood with respect to HSV survival. Adsorption of HSV to the lymphocyte surface did not differ between placental and adult cells. Placental blood permitted greater survival of HSV than adult lymphocytes. T-cell-enriched lymphocytes appeared to be slightly more permissive than T-cell-depleted lymphocytes, but these differences were not statistically significant and apparently less than adult-placental blood differences. These findings lend support to the hypothesis that intracellular changes common to various neonatal lymphoid populations may permit or promote dissemination of HSV in the neonate.