We report on eight patients who developed white lichenoid lesions of the buccal mucosa during the course of human immunodeficiency virus infection. In five patients the lesions appeared after the administration of zidovudine, in two after the intake of both zidovudine and ketoconazole, and in one after ketoconazole. In the majority of cases, lesions presented as bilateral reticular keratosis or atrophic changes of the buccal mucosa. Three patients manifested lichenoid atrophic changes of the dorsum of the tongue. The histopathologic features were hyperkeratosis, epithelial atrophy, basal cell liquefaction, and the presence in the lamina propria of either a patchy or diffuse lymphocytic infiltrate. All specimens tested negative for Epstein-Barr virus and human papillomavirus. Our study suggests that lichenoid lesions of the buccal mucosa, similar to what has been described as lichenoid drug reactions or idiopathic lichen planus, can be observed during human immunodeficiency virus infection and that administration of zidovudine and ketoconazole should be considered as a possible cause.