Three patients with an acute myeloid leukaemia (AML) showed a deletion of the short arm of chromosome 7 with loss of the deleted material. The 7p- anomaly originated from either a terminal or an interstitial deletion and it represented the only karyotypic aberration in all the three cases. According to the clinical, morphological and immunological features of this series of patients, a 7p- chromosome appears to be associated with a group of AML with myelodysplastic features in the bone marrow, including secondary disorders in patients treated for a previous malignancy.