From 1972-1983 53 patients underwent bone marrow transplantation. The median age was 18 years (3-41). 27 patients suffered from severe aplastic anaemia, 22 patients had acute leukaemia and 4 patients had chronic granulocytic leukaemia in chronic phase. Out of 22 patients with acute leukaemia, 2 had florid leukaemia, 2 had an early relapse and 18 patients were in first or second remission of their disease. 2/53 patients received a syngeneic transplant, 51/53 patients an allogeneic transplant. 47/51 patients had a HLA-A, B, C-identical, MLC-negative sibling donor, 1/51 had a HLA-A, B-C-identical, MLC-positive sibling donor, 2/51 a HLA-phaenotypical identical parental donor and 1/51 a HLA-identical, MLC-negative unrelated donor. The comparison of the results obtained in patients with severe aplastic anaemia transplanted from 1972-1979 with those transplanted from 1980-1983 shows that the bone marrow transplantation has to be performed in an early stage of the disease before the patients become multiple transfused, sensitized and severely infected and that the conditioning regimen for polytransfused patients has to be more intensive than in untransfused patients. From the patient group transplanted 1972-1979, only 1/14 patients is a long-term survivor in contrast to 8/13 patients transplanted from 1980-1983. 11/22 patients with acute leukaemia are alive between more than 5 years and 14 days after bone marrow transplantation. Only 1/4 patients, who were transplanted not in remission, is alive.(ABSTRACT TRUNCATED AT 250 WORDS)