Abstract: animals (given 2 mg. on the day preceding and on the day of the encephalitogenic injection) were reported as manifesting an early onset and unusual severity of neurological disturbance, while the disease was also thought to be histologically intensified.In a much larger series of prednisolone-treated animals (40) we could not substantiate these findings, though it must be conceded that we administered 0.1 ml.(= 2 mg.) daily on the lines employed in clinical trials. SUMMARYEvidence is presented that corticotrophin is more effective than prednisolone in mitigating the experi- mental encephalomyelitis induced in guinea-pigs by the inoculation of brain emulsion with Freund adjuvant.We thank the board of governors of the Royal Victoria Infirmary, the Multiple Sclerosis Society, and the North- East Multiple Sclerosis Trust for their generous financial support.We are grateful to Mr. D.