By indirect immunofluorescence microscopy (IIF) we have localized glycoprotein D (gD) of herpes simplex virus-infected cells to the vinculin-containing junctional areas and to the focal adhesion sites on the ventral surface of the cells. Double-staining IIF showed that gD and vinculin co-distributed in the infected cells and treatment of the infected cells 4 h post-infection with rabbit antibodies to gD prevented attachment of the cells to the growth substratum. Our results therefore support the hypothesis that gD plays a central role in the social behaviour of infected cells.