Twenty-five institutions are participating in a randomized trial of the E.O.R.T.C. for improvement of remission incidence, disease-free interval and survival in adult acute non-lymphocytic leukemia. In order to delay the time of relapse, an intensive cyclic therapy is employed early after achievement of complete remission (C.R.) using either the same drugs of the induction regimen or rotating combinations of alternative drugs, e.g. mAMSA, 5-AZA and HD-Ara C. So far 266 patients entered the trial with a median age of 45 yrs. The overall C.R. rate is 71%; 52% of the responders reached C.R. after 1 cycle of induction treatment. 10% of the patients died within the first 7 days of induction or due to hypoplasia, 13% were absolute resistant to this regimen. Fifty-eight patients are randomized to 'maintenance' arm I, 54 to arm II, 79/112 patients are still under study. Treatment toxicity is tolerable. In 7% and 3% excessive toxicity was a reason for going off study during induction or 'maintenance'. As far as remission duration or survival within the two treatment arms is concerned, it is too early to draw any conclusions.