Three consecutive patients considered to have end-stage acquired aplastic anaemia were given 100-160 mg/kg antilymphocyte globulin (ALG) i.v. followed by an infusion of 2-3.8 x 10(8) nucleated marrow cells/kg i.v. from HL-A one haplotype-identical, MLC-positive family donors. All patients showed autologous marrow reconstitutions lasting now 2-3 1/2 years. No clear-cut evidence of marrow engraftment could be established and no graft-versus-host disease was seen. It is assumed that these patients had some normal pluripotent haemopoetic stem cells which proved to be able of endoreduplication and of going into cycle after ALG conditioning and allogeneic marrow transfusion.