Recent studies suggested herpes simplex virus type 1 as a major etiologic factor in Bell's palsy. To analyze different aspects of facial nene infections, Swiss mice were inoculated with HSV-l in tongue (41 animals) and auricle (44). Nineteen mice developed unequivocal signs of nevous infection, but only in 1 mouse was evident a facial palsy. Mice were sacrificed at different intervals from inoculation, and facial nerves, Gasser ganglia and brain stem were obtained to test the presence of HSV-1 by nested PCR and viral culture. Virus was detected in the 3 types of samples, but identification was more frequent in animals injected in tongue and sacrificed during the acute infection. Nested PCR was far more sensitive than culture, particularly during viral latency. According with our results, HSV-1 could origin facial palsy, but is possible that lesions are immunomediated and localized at brain stem.