This retrospective survey of the EBMT Leukaemia Working Party describes 78 patients with myelodysplasia (MDS) or secondary acute myelogenous leukaemia (sAML) who received an allogeneic bone marrow transplant (BMT). The status of underlying disease at the time of transplantation was prognostic for the 2-year disease-free survival. Thirty-four patients received intensive chemotherapy prior to the conditioning for BMT. The 2-year disease-free survival was 60% for the 16 patients transplanted in complete remission. The results were significantly less favourable for those with more advanced disease who only partially responded to prior intensive chemotherapy (2-year disease-free survival: 18%) while none of those who either relapsed or were resistant to chemotherapy survived BMT for 2 years. Forty-four patients had not received any prior intensive chemotherapy. The disease-free survival at 2 years after BMT was 58 +/- 19% when a patient was transplanted for refractory anaemia (RA(S], 74 +/- 14% for refractory anaemia with excess of blasts (RAEB), 50 +/- 16% for RAEB in transformation (RAEBt), and 18 +/- 11% for secondary AML. Allogeneic BMT can therefore be considered as curative treatment for patients with MDS. Patients with sAML who have a histocompatible donor should be given chemotherapy intensive enough to induce complete remission. If this is achieved these individuals have a prognosis comparable to those with de novo AML in first remission after BMT.