The present case, together with other reports reviewed herein, defines a new subtype of therapy-related acute myeloid leukemia (t-AML). This variant of t-AML is characterized by a short interval from initial drug therapy to bone marrow dysfunction and monocytic morphology without trilineage dysplasia. Unlike classic t-AML, which frequently has abnormalities of chromosomes 5 and/or 7, this new subtype is characterized by rearrangements involving band q23 of chromosome 11, most commonly a 9;11 translocation. The majority of patients with this subtype t-AML had prior cytotoxic therapy with topoisomerase II-reactive drugs including anthracyclines, epipodophyllotoxins, or actinomycin D, combined with either an alkylating agent or cisplatin. This association of prior therapy which includes topoisomerase II-reactive agents and a rapidly appearing t-AML involving the monocytic line and chromosome 11 requires additional study.