We report the occurrence of a malignant melanoma in a patient with neurofibromatosis (von Recklinghausen's disease; NF 1). Neurofibromatosis, like malignant melanoma, is believed to be a disorder of neural crest origin, and is associated with a number of different malignancies, but a definite association between cutaneous malignant melanoma and neurofibromatosis has not been established. We describe a patient with a malignant melanoma and with neurofibromatosis, and review the literature pertinent to this topic. The malignant melanoma was not related to a café-au-lait patch or congenital naevus. The paucity of reports of patients with neurofibromatosis associated with cutaneous malignant melanoma suggests that these diseases probably do not occur together with any greater frequency than that determined by chance alone.