The occurrence of acquired demyelinating neuropathy on autoimmune background is most fre-quently preceded by a viral infection, and in half of the cases the etiologic factor is not determined. The syndrome is characterised by muscular weakness in the proximal limbs, initially affecting the lower extremities, and subsequently affecting the higher sections of the body - the trunk, chest and upper limbs. It may be accompanied by paresis of the facial muscles, swallowing disorders and dysar-thria, and in more sever cases - by disorders of the autonomous system. The diagnosis of the syndrome is based on clinical symptoms, in doubtful cases the determination of the level of protein in the cerebrospinal fluid is helpful (an increase by even several g/l), and an EMG examination (decreased nerve conduction velocity or total blockage). The treatment of choice in an acute form of the syndrome is plasmaferesis; however, in the case of the lack of effectiveness or possibilities of performing plasmaferesis, an alternative treatment is the intravenous administration of immunoglobulins