From July 1984 the five Nordic countries (Denmark, Finland, Iceland, Norway and Sweden) have registered all children with acute myeloid leukaemia (AML) and treated them on two consecutive protocols of different intensity (NOPHO-84 and NOPHO-88). We probably have information on every child with this diagnosis in our region. We found an annual incidence of AML of 0.7 new cases per 100,000 children < 16 years of age. We observed a distinct peak of incidence in the first 2 years of life. Children with Down's syndrome accounted for 13% of all cases. Eighty of 105 cases treated on NOPHO-84 achieved remission (78%). In NOPHO-88, 100/118 patients entered remission (85%). The overall event-free survival (p-EFS) for the two studies was 0.32 for NOPHO-84 and 0.42 for NOPHO-88. The majority of relapses occurred within 2 years of diagnosis. When looking for prognostic factors the strongest significant adverse factor found was male sex. Children with Down's syndrome (n = 35) had a very favourable outcome if they received therapy according to protocol, and infants (n = 26) had a superior outcome compared to children 1-2 years or > 10 years of age at diagnosis.