Treatment decisions for the patient newly diagnosed with chronic myeloid leukemia have never been more difficult. Interferon alfa has improved the median durations of chronic phase and survival for all patients and especially for those who achieve cytogenetic responses. The addition of cytosine arabinoside improves outcome still further. The place of autografting, particularly now that it is possible to obtain Ph-negative stem cells for transplant, has yet to be determined. For a patient with an HLA-matched related or unrelated donor, the decisions if and when to proceed to transplant are controversial. In this paper, the prognostic factors affecting the outcome of transplant are discussed with particular reference to recently available data, and attention is drawn to the development of decision-making models in this fascinating and challenging disease.