Double minute (dmin) chromosomes were found in 17% of bone marrow cells in a 66-year-old woman with acute myelogenous leukemia (AML) which was resistant to treatment with cytosine arabinoside and daunorubicin hydrochloride. She died within 3 weeks of developing symptoms. The cells had a range of 36 to 49 chromosomes with a mode of 47 and a variety of structural and numerical chromosome abnormalities, as well as the presence of 1 to 10 C-chromatin negative dmins. In leukemias few cases with dmins have been reported. However, we suspect other cases may have been overlooked because of the very small size of some dmins. We hope that this report will direct attention to the presence of dmins in leukemic cells and, in particular, stimulate attempts to determine if there is a correlation between their presence and the resistance of the cells to chemotherapy or the rate of disease progression.