A case diagnosed to have the lesion of pachydermatocele type of Recklinghausen's disease in a 28-year-old female was studied mainly by means of fluorescence method (Falck and Hillarp). Histopathological examination revealed that the lesion was composed of Ota's nevus-like changes in the epidermis to the middermis and of proliferation of neurofibromatous tissues coexisting with melanin-producing cells in the lower dermis to the subcutaneous adipose tissue. Melanin-producing cells in the neurofibromatous lesion were shown by fluorescence method to have characteristics of nevus cells rather than of melanocytes. Innervation of monoaminergic and cholinergic nerves was not found to the arteries in neurofibromas. These findings are thought to suggest that the abnormalities of not only Schwannian cells and melanocytes of neural crest origin but also of nevus cells and autonomous nerves of neural crest origin are related with the pathogenesis of pachydermatocele type of Recklinghausen's disease.