The authors study the vitamin B12 absorption (Schilling test) in 16 cases with neurological symptoms of subacute combined degeneration of the spinal cord and with constitutional or acquired (post-gastrectomy) gastric achlorhydria or hypoclorhydria. No correlation was evidenced between vitamin B12 absorption and the degree of the neurological symptomatology as a whole, or the disorders of the vibration sense. In the patients with deficient absorption pyramidal signs have prevailed; in the group with normal absorption peripheral signs showed predominance over the signs of damage of the corticospinal tracts.