23 out of 151 patients of the childhood AML study BFM-78 were less than two years of age at the time of diagnosis, 10 of them being less than one year old. The incidence of M5-subtype was high in infants with 12/23 (52%) compared with 20/128 (16%) in those 2 to 17 years of age. The percentage of boys was 44% in the young children compared with 56% in the older ones. Initial skin infiltrations were seen in five infants with monoblastic subtypes (M4, M5) and in only three patients more than two years of age. The incidence of liver and spleen enlargement greater than or equal to 5 cm below the costal margin was significantly higher in young children. Due to infectious complications frequent therapy-free intervals and/or reduced drug dosages were necessary in the 8-week induction treatment regimen. The prophylactic cranial irradiation with 12 Gy in the first year of life and 15 Gy in the second year has so far not caused any long-term sequelae. The results were similar to those in older children: 18/23 (78%) of the infants achieved complete remission compared with 101/128 (79%) of those 2 to 17 years old. With a follow-up period of 16 to 49 months the probability of continuous complete remission (disease-free interval) was 52% in children under the age of 2 and 54% in those more than 2 years of age. We conclude that with the improved prognosis an intensive chemotherapy is justified in infants with acute myelogenous leukemia.