In a prospective study 100 AML cases were randomized in two groups and underwent remission induction treatment in 4 departments with "Ara-C c. inf. from the first to the eight day plus Adr. from the first to the third day" or "Ara-C + 6-TG + Adr., 6 + 6 + 2 days". The CR patients were divided into two subgroups. Subgroup A obtained maintenance therapy with 5 day course of Ara-C s.c. in addition to 6-TG, Vincristine plus Prednisone and Adriamycin sequentially, with each cycle repeated at 6 week intervals. Subgroup B obtained the calf thymus extract (TFX-Polfa) between the cycles additionally. The current results of remission induction treatment are similar to "8 + 3" and "6 + 6" regimens as measured by the CR rate (45% and 44%), survival curves (survival after 24 months - 23% and 28% respectively) and relapse rates (3.5%/pt.mo.obs. and 5.3%/pt.mo.obs.). It is still too early to evaluate the efficacy of this maintenance treatment, because the programme is still open to patient entries. At present 13 patients received maintenance regimen A and 12 patients received maintenance regimen B, with an average survival being equal to 14 and 13.5 months respectively.