DNA hybridization kinetic analysis of cellular DNA following high multiplicity infection of non-permissive XC cells by herpes simplex virus type I showed that HSV DNA penetrates to the nucleus of the cell but that the number of virus DNA copies present in each cell quickly begins to decline. There did not appear to be any net virus DNA synthesis and the loss of virus DNA copies continued until there was approximately one per haploid genome equivalent. HSV-2 likewise did not show any detectable virus DNA replication. The residual virus information was stable for more than 48 h. CsCl density gradient analysis of the infected cell DNA suggested an association between the HSV DNA and that of the cells. Network analysis also supported the suggestion that a stable association between the virus DNA and host DNA begins shortly after infection. Cell division resulted in the segregation of the virus DNA but not its loss from the cell population. Virus-specific RNA synthesis was easily detectable and 40 to 50% of a labelled DNA probe was converted to an RNA:DNA hybrid.