A retrospective analysis was performed on 235 elderly acute myelogenous leukaemia (AML) patients aged 60 years or more, consecutively admitted to a single haematological department during a 10-year period from 1980 to 1989. 46% of patients received only conventional induction chemotherapy. The rate of inclusion in EORTC cooperative clinical trials was significantly lower than for younger patients despite specific protocols proposed for the elderly since 1983, thus confirming the important selection bias of most published series on elderly AML patients. Compared with treatment results in patients < 60 years, complete remission (CR) rate was lower (33.3% v 65.4%, P < 0.0001), with a marked drop in patients older than 70, and induction death rate was higher (21.3% v 12.5%, P = 0.04). Intrinsic characteristics of leukaemic cells, especially expression of the MDR1 gene, in vitro growth of the leukaemic clonogenic cells and sensitivity to daunorubicin-(+)cytosine arabinoside, did not differ according to age, except that there was a higher incidence of previous myelodysplastic syndromes and a lower incidence of good prognostic cytogenetics in the elderly patients. Thus, treatment failure in elderly AML patients appears to be mainly due to host-related factors (especially performance status and age < or > or = 70 years), and to inadequate treatments. Some elderly patients may have been undertreated because of the planned anthracycline dose reduction, resulting in a higher rate of 'resistant' AML, i.e. patients surviving the induction period without entering into CR, than in younger patients (45.4% v 22.1%, P < 0.0001). 11 patients (4.7%) with untreated or 'resistant' AML survived more than 1 year, while receiving only supportive care. These slowly progressive AML patients were characterized by a good performance status, and lower circulating blast cells and bone marrow blast counts.