It is apparent from the accompanying Table 9 and Figure 5, that transplantation offers an improved survival in AML. The use of CSA has made possible the technique of a mis-matched transplant, but as yet an unrelated donor has not been used. It may be that tolerance is more easily established with a one haplotype mis-match than with a completely unrelated person who may, nevertheless, be HLA identical. Clearly this would be an exciting project for the future, provided that all problems concerning relapse of disease and GvHD are overcome, and will also probably depend upon improvements in tissue typing techniques. (table; see text) Certainly we would now recommend this form of treatment to all patients under 40 years of age, in first remission from AML. Patients above this age, have responded less well and have been prone to more complications. We do not as yet know whether a complete remission is essential prior to embarking on a graft; certainly a few patients have been in early relapse, and this does not seem to have necessarily produced a poor outcome. Florid relapse at the present time is a definite contra-indication and no patients have been grafted in this situation. It will be noted that results for acute lymphoblastic leukaemia and chronic granulocytic leukaemia are bad. The first group were grafted early in the programme, but the number of relapses was extremely high and was accompanied in many circumstances by interstitial pneumonitis. Transplantation in chronic granulocytic leukaemia, a disease in which the prognosis has not improved for the past 20 years, has also not been successful except in one syngeneic graft. Two of the three deaths were in previously treated patients, one in blast transformation, but the third was virtually untreated and GvHD was a very serious problem indeed. Other reports of grafting for CGL have been discouraging except in twins. All these deaths occurred early. Whether this therapeutic approach will remain a treatment of choice remains to be seen, but we are very encouraged by our progress so far, although much work remains to be done.