Three cases of 'focal epithelial hyperplasia' (FEH) of the oral mucosa observed for the first time in Switzerland are reported. The patients were of Turkish and North African extraction. The lesions of FEH were multiple, painless, located at various sites of the oral mucosa including the tongue, in the form of either soft papules or hard nodules. Evidence of a human papilloma virus origin was ascertained. Among the 1,067 cases reported in the literature and reviewed for this study, this condition has been described to occur among American Indians, Eskimos and Cape Coloureds; also in Israeli and European cases the disorder was often reported in individuals of Turkish or North African extraction.