It is apparent that treatment of Hodgkin's disease can be complicated by the development of secondary leukaemia. Most such leukaemias are of the non-lymphocytic type. We describe here a patient treated for Hodgkin's disease with chemo- and radiotherapy who developed secondary acute lymphoblastic leukaemia with a non-random chromosomal abnormality t(4;11). The frequency of such cases is assessed by a literature review and evidence for their pluripotent cell origin is discussed.