The concomitant presentation of acute myeloid leukemia (AML) and chronic lymphocytic leukemia (CLL) is rare with so far only eleven cases reported. In addition, the achievement of complete remission (CR) in CLL is exceptional and generally not assessed by immunophenotypical investigations. We report a case with a simultaneous occurrence of AML and CLL in which, in addition to the complete remission of AML, an eradication of the CLL clone was obtained following high-dose cytosine arabinoside. The immunophenotypic investigation of minimal residual disease showed that less than 1 x 10(-3) CD19+/CD5+ B-cells remained in bone marrow.