The clinical use of S.E.R. (Somesthesic Evoked Responses) from the lower limbs has peculiar prognostic value in cases of spinal pathology with clinical signs of transection, where other neuroradiological investigations are not helpful. However, in the present case of acute trasverse myelitis, persistence of an evoked response from the lower limbs was never followed by signs of recovery below the lesional level, while autopsy showed a complete degeneration of the descending spinal pathways with a good preservation of the posterior roots. The limits of this technique appear connected to the fact that the afferent volley of the S.E.R. travels exclusively along the posterior roots, not allowing a definite prognostic evaluation about function of the remainder descending pathways.