A balanced translocation involving 11q23 (MLL gene) could be observed in therapy related leukemia (TRL) patients generally treated with topoisomerase II inhibitors. Few reports have been published on TRL following docetaxel administration. Herein, we report a patient who developed acute myelomonocytic leukemia (AMMoL) with t (9; 11) (p22; q23) following chemotherapy mainly consisted of docetaxel for advanced prostatic carcinoma. A 69-year-old man was treated with a systemic chemotherapy containing docetaxel (total dose = 585 mg) for hormone-refractory metastatic poorly differentiated prostate carcinoma. Although, no disease progression of the prostatic carcinoma was observed, AMMoL with t (9; 11) (p22; q23) developed only ten months later from the administration of docetaxel. Docetaxel was considered to be the cause of TRL because of the presence of t (9; 11) (p22; q23) translocation and clinical course.