Frequency and nosological attribution of demyelinating polyneuropathies in patients with diabetes mellitus and alcoholism were determined. Eighty-six inpatients with alcoholic (n=46) and diabetic (n=40) polyneuropathy were examined clinically and using electroneuromyography (ENMG). A demyelinating pathogenetic variant was identified by clinical and ENMG data in 27 (31%) patients. Nine patients (33%) had dysimmune polyneuropathies (acute and chronic inflammatory demyelinating polyneuropathy). Polyneuropathies were specified as toxic/metabolic with the prevalence of a demyelinating component within the main disease in 18 (67%) patients. Clinical and ENMG-signs of the demyelinating variant of alcoholic and diabetic neuropathy are presented. The efficacy of the antioxidant berlition was shown for toxic/metabolic polyneuropathies while the addition of immune modulators was needed for treatment of dysimmune polyneuropathy.