RESUMEN La degeneracion combinada subaguda es un desorden neurologico que afecta los cordones posteriores de la medula y se manifiesta precozmente con disestesia, parestesias y astenia severa. En pacientes de riesgo, es la manifestacion inicial (y a veces unica) de una deficiencia de vitamina B12. El cerebro, el nervio optico y los nervios perifericos pueden afectarse igualmente. Presentamos catorce casos de degeneracion combinada subaguda por deficiencia de vitamina B12, con niveles bajos y anemia en la mayor parte de pacientes. Una revision de la literatura muestra tambien estados carenciales en grupos poblacionales pobres de adultos mayores con otros factores de riesgo; y deficiencias subclinicas con depositos hepaticos de vitamina B12 casi exhaustos. Puede haber clinica neuropsiquiatrica en casos sin niveles bajos de vitamina B12 ni anemia. Palabras clave: Anemia, astenia, apalestesia, Romberg, degeneracion combinada subaguda, vitamina B12. SUBACUTE COMBINED DEGENERATION, MEGALOBLASTIC ANEMIA AND NEUROPSYCHIATRIC MANIFESTATIONS Clinical picture of fourteen cases with deficiency of cianocobalamin ABSTRACT Subacute combined degeneration is a neurologic condition that involves spinal cord posterior columns, presenting early with disesthesia, paresthesia and severe asthenia. In patients at risk, it is the first (and sometimes the only) manifestation of a vitamin B12 deficiency. Brain, optic and peripheral nerves may be equally involved. We report fourteen cases of subacute combined degeneration and vitamin B12 deficiency as shown by low levels and megaloblastic anemia in most cases. A review of the literature was undertaken, remarking the importance of nutritional deficiencies seen in impoverished elderly people with additional risk factors; subclinical cases with liver storages almost exhausted. There could be a neuropsychiatric picture even without anemia o low vitamin B12 levels. Key words: Anemia, weakness, apalesthesia, Romberg, subacute combined degeneration, Vitamin B12.