This case of subacute encephalomyelitis with a hyperekplexia type syndrome was characterized histologically by marked lymphomonocytic infiltrates, nodules of microglia, evidence of neuronophagia. These findings suggested a viral infection. The clinical peculiarities of this encephalomyelitis are explained by the elective site of the lesions in the grey substance of the spinal cord, of the tegmentum of the medulla oblongata and pons and of some nuclei of the extrapyramidal system.