Although herpes simplex virus type 1 (HSV-1) does not induce apoptosis in infected HEp-2 cells, in the presence of cycloheximide infection induced apoptosis with characteristic morphological changes as well as endonucleosomal DNA cleavage. The induction of apoptosis without de novo protein synthesis suggests that a structural protein of the HSV-1 virion is responsible for the observed apoptosis.