SummaryA white male patient 38 years old has contracted leprosy in Africa. After several years of incubation, dermatological manifestations occured (erythemato-squamous patches mainly located on the trunk) together with neurological signs (distal anesthesia of lower limbs going up to the thighs and localized zone of thermoanalgesia around the right forearm). Histological and immunological findings enabled to classify the disease within the«border-line»group, with a lepromatous tendency. A review of recent data concerning leprous neuritis emphasizes its close relationship with the immunological response of the host. The therapeutic prescriptions resulting from this relationship are described.