Report of three cases of Guillain-Barré's syndrome with considerations from the view point of recent developments in its therapeutics, experimental studies and virulogy. Guillain-Barré's syndrome is included by the author among the demyelinating diseases of the central nervous system, on the basis of the cases here presented and others reported in the literature. Cases 1 and 2 had satisfactory results out of rehabilitation and reeducation; case 1 included papilledema which disappeared spontaneously; case 2 showed a predominant dorsal funicular syndrome. Case 3 was treated with ACTH (daily intravenous injection of 15 mgm. in 500 c.cm. of a 5 per cent (glucose solution) with complete recovery in about two weeks, including a change of the T electrocardiographic wave the patient presented before treatment.