Monospecific rabbit antisera against purified herpes simplex virus type 1 (HSV-1) gB, gC or gD antigens or polyvalent rabbit antiserum against equine herpesvirus type 1 (EHV-1)-infected cells was used in Western blotting to identify antigenically related proteins in cells infected with HSV-1, HSV-2, bovine mammillitis virus or EHV-1. Monomeric and oligomeric polypeptides related to HSV-1 gB were found in cells infected with each of the four herpesviruses. The gC antiserum was specific for HSV-1 and the gD antiserum reacted only with polypeptides in HSV-1- or HSV-2-infected cells. Neither gC nor gD antiserum revealed the existence of oligomeric forms of the glycoproteins with the single exception of HSV-1 strain KOS which had a heat-unstable high molecular weight form gD. The EHV-1 antiserum reacted with high molecular weight polypeptides of the same mobility as the oligomeric form of gB in cells infected with each of the four herpesviruses.