We report a case of granulocytic sarcoma presented as a recurrent breast tumor in a 42-year-old woman with no history of leukemia. The case was initially diagnosed as malignant lymphoma on a previous biopsy specimen and she refused chemotherapy. At the time of recurrence of the breast tumor, the patient showed full-blown features of leukemia. This case of rare tumor suggests that differential diagnosis should be considered when malignant lymphoma of the breast is detected.