In a prospective study running between 1981 and 1983, a group of 156 adult (under 60 years of age) patients with de-novo acute myelogenous leukaemia were randomly assigned to receive a daunorubicin, cytosine arabinoside and thioguanine combination or a regimen containing lower dosages of these drugs but also containing etoposide and vindesine. Patients who entered complete remission received maintenance therapy for 2 years. The survival and remission duration curves of the two groups were exactly superimposable and for this long-term analysis all patients have been considered together. The follow-up times range between 84 and 104 months. Actual survival at 7 years is 15% (95% confidence intervals 9-20%), with a stable curve thereafter. Actual probability of continuous complete remission at 7 years is 22% (95% C.I. 13-31%) with a stable curve beyond that point. These findings, similar to those of the few other studies of chemotherapy with comparable follow-up times, suggest that only a small fraction of adult patients become long-term survivors, irrespective of the precise type or amount of antineoplastic agents administered.