RESUMEN
A review of the present results of bone-marrow transplantation (B.M.T.) in severe aplastic anaemia is presented. Nowadays, there is little doubt that for patients with severe aplastic anaemia the treatment of choice is the B.M.T. provided always that a suitable donor exists. If the patient is fortunate enough to have a normal identical twin, the syngeneic B.M.T. without immunosuppresive conditioning must be performed. This is usually successful, though in some patients failures can be observed due to probable immunological interference. This can be overcome by a new syngeneic B.M.T. preceded by immunosuppression. The usual type of suitable donors is an HLA-identical (including locus D) sibling (allogeneic B.M.T.). Approximately 50% of patients treated in this way can become long-term survivors. The chief complications causing mortality from the allogeneic B.M.T. are graft rejection and graft-versus-host-disease (G.V.H.D.). In order to reduce the graft rejection rate, transfusions from marrow-donor and relatives prior to the transplantation should be avoided. Other probable factor influencing the final outcome of the allogeneic B.M.T. are the interval diagnosis-transplantation, age of the patient, marrow cell dose, the difference of sex between the donor and the recipients and others. Semi-incompatible and incompatible allogeneic B.M.T. are briefly considered.