Summary. Cytogenetic analysis was successfully performed at diagnosis in 283 patients with de novo acute myeloid leukaemia (AML), including eight children aged 6–15 and 275 adults. Mean age was 50.3 (range 6–86) and the M/F ratio was 1.23. 214 patients were treated by intensive chemotherapy and 75.2% achieved complete remission. Patients with inv(16) and t(8;21) had very high CR rates whereas those with complex cytogenetic abnormalities (with or without involvement of chromosomes 5 and/or 7) had a poor response to therapy. Other karyotypic abnormalities and normal karyotypes were associated with intermediate CR rates. In a multivariate analysis, cytogenetics were the best prognostic factor of the achievement of CR, followed by age and platelet count. Median actuarial disease-free survival (DFS) of the patients who achieved CR was 19 months. No significant differences in actuarial DFS were found according to karyotype. However, no relapses were seen in patients with inv(16) and t(9;11) or its variants. Conversely, the median DFS was only 12.5 months in patients with t(15;17). Median actuarial DFS was 24 months in patients with t(8;21), but a high incidence of early relapses were seen, and the actuarial DFS was only 54% at 12 months. Patients with trisomy 8 also had a median actuarial DFS of 24 months. Our findings do not support the previously reported ‘favourable’ prognosis of t(15;17) translocations. They suggest that, although it is characterized by a high CR rate, t(8;21) might be associated with a high incidence of early relapses and that, finally, inv(16) might be the only ‘favourable’ cytogenetic rearrangement in AML. Furthermore, the prognosis associated with t(9;11) or its variants (at least in adults), and trisomy 8 might be less severe than suggested in other studies.