The authors present 15 observations of a medullary syndrome of the non-syringomelic type, in patients with Arnold-Chiari's malformation (type I; 13 times - type II; twice), verified surgically, and without severe malformations of the occipito-vertebral articulation. Brown-Sequard's disease was present in 6 cases, subacute combined degeneration in 2 cases, and pyramidal lesions were very predominant in two other cases. The last 5 cases had cordonal signs associated with signs of disturbance of the anterior horns in the medulla, affecting all four limbs, and more especially the lower limbs. In four cases the medullary cavity was exposed, and in two cases extended along the whole length of the cord up to the terminal cone. The literature is reviewed and diagnostic and pathogenic problems raised by these myelopathies are discussed. They merit systematic investigation.