This report describes three patients who have in common an occurrence of ocular epithelial herpes infection following a penetrating keratoplasty for a corneal opacity unrelated to herpesvirus infection. It may be that patients undergoing episodes of graft rejection are at increased risk for the reactivation of herpesvirus latent in the trigeminal ganglia, and corticosteroids should be used with this in mind. Because virtually all adults have been exposed to herpes and therefore harbor latent virus, a viral etiology should be considered for lesions in post-penetrating keratoplasty patients. Although the occurrence of this possibly rejection-related reactivation of herpes simplex virus is undoubtedly rare, management of potential cases of this nature should take this possibility into account.