The analysis of the treatment results of the co-operative therapy studies BFM 78 and 83 for the treatment of acute myelogenous leukemia in children revealed the following risk factors: Death before the onset of therapy and early death occurred more frequently in children with acute monoblastic/monocytic leukemia and in children with initial WBC of greater than 100,000/microliters than in the other patient groups. The remission rate was lower in children with an initial WBC greater than 100,000/microliters (56%) than in children with an initial WBC less than 100,000/microliters (86%). In study BFM 78 the probability of a relapse free interval of 6 years is significantly lower in children with an initial WBC greater than 100,000/microliters (pCCR = 28%; SD 11%) than in children with an initial WBC less than 100,000/microliters (pCCR = 64%; SD 10%). The median follow up time is 4 3/4 years (range 2 3/4-6 3/4 years). The probability of an event free interval of 3 years was significantly lower in children with initial involvement of the CNS (pCCR = 24%, SD 12%) than in children without involvement of the CNS (pCCR = 50%; SD 5%).