Segmental neurofibromatosis (neurofibromatosis type V) is a rare disorder characterized by café-au-lait macules and neurofibromas, or only neurofibromas, limited to one region of the body. Three patients with segmental neurofibromatosis are described, and cases of this condition in the world literature are reviewed. Segmental neurofibromatosis has only been described in 82 patients, including our three. The median age at onset was 28 years and the incidence was higher in women (58%). The neurofibromas most commonly occupied either a cervical or thoracic dermatome and were unilateral, occurring more often on the right side (43 patients) than the left (34 patients). Café-au-lait macules were present in 26% of patients. Axillary freckling was described in only nine patients. Disease-associated systemic involvement was uncommon. Most patients with segmental neurofibromatosis (93%) do not have a family history of neurofibromatosis. (J Am Acad Dermatol 1997;37:864-9.)