The authors report the early and late results of the use of ACTH in 4 cases of achylic demyelinating neuropathy (so-called subacute combined degeneration of the spinal cord). Daily doses of 12.5 or 15.0 mgm. of corticotropin were given by continuous drip method, without any other associated drug which could interfere in the results. By employing a semi-quantitative method for evaluation of the clinical effects, an average improvement of 26 per cent was found, the same results being observed soon after the treatment and by a follow-up from 3 to 6 months. The effects on the pyramidal syndrome were particularly satisfactory both early and lately; the improvement of the dorsal funicular syndrome was not so long lasting. Treatment with vitamins B1 and B12 six months after the use of ACTH, in 3 cases, caused no further change in the clinical picture.