We have analysed Epstein-Barr virus (EBV)- and herpes simplex virus (HSV)-infected cells for evidence of antigenic conservation of virus-coded proteins. Immunofluorescence and Western blot analyses of EBV-transformed cell lines demonstrated the presence of proteins that are antigenically related to the HSV alkaline DNase, infected cell-specific protein 34/35, glycoprotein B, thymidine kinase and the major DNA-binding protein. These proteins were characterized on the basis of Mr and possible kinetic class.