DESPITE several years of speculation and considerable clinical trial, the efficacy of corticotropin or adrenal cortical steroid compounds in the treatment of demyelinating diseases remains doubtful.1-4 Of these diseases acute disseminated encephalomyelitis would be expected to respond best to the drugs because of its resemblance clinically to the experimental disease, "allergic" encephalitis, which is definitely inhibited by the compounds.1,5-7 Clinical data seem to have borne out this predicition,8-14 but reports are sparse and controlled studies are absent. The treatment, therefore, while generally used, is not firmly established. The problem is particularly difficult since the clinical diagnosis can never be proven in life, and the disease is difficult to differentiate from other encephalitides. The following five cases are reported to add confirmation of clinical effectiveness of corticotropin and adrenal steroids in probable cases of acute disseminated encephalomyelitis and, in particular, to call attention to the inadvertent natural