The leukaemias are a diverse group of bone marrow malignancies. In general, the acute leukaemias are potentially curable with standard combination chemotherapy but the chronic leukaemias, despite a more prolonged, indolent course, are incurable. Newer antimetabolite agents offer the promise of improved survival in the chronic leukaemias of lymphocytic origin. Although it may not be indicated for all types and is generally suitable only for younger patients, bone marrow transplantation provides improved prospects for cure for most types of leukaemia and the only chance of cure for some.