Facial nerve palsy has long been considered to have an infectious etiology. Recent diagnostic analyses in children and adults have provided convincing evidence that reactivation of varicella-zoster virus (VZV), sometimes during infectious mononucleosis, can lead to cranial nerve VII palsy. The site of reactivation from latency is the geniculate ganglion. Virus most likely enters the ganglion during chickenpox, via the sensory branches of the facial nerve located on the ear and tongue. Retrospective reviews suggest that patients with VZV-related facial nerve palsy have poorer outcomes than other cases of Bell’s palsy. Therefore treatment with acyclovir is suggested when VZV reactivation is likely.