The presence of abnormal feeding vessels in plexiform neurofibromata of the head and neck has been demonstrated by angiography in three patients. Attention is drawn to the possibility of dangerous bleeding in the treatment of these lesions. Two other patients presented with a similar lesion over the trunk: in one patient there was excessive bleeding during surgical excision but not in the other, despite their very similar clinical appearances. It is suggested that two varieties of plexiform neurofibromata exist which are distinguishable only by angiography: those with a normal vasculature and those with a plethora of abnormal vessels forming an integral part of the lesion along with the neural and fibrous elements (haemangioneurofibroma). A method of treatment is proposed based on pre-operative embolisation followed by complete surgical excision. The futility of pre-operative vessel ligation is confirmed.