Granulocytic sarcoma (GS) is a rare extra-medullary occurrence of a malignant neoplasm of immature granulocytes. To our knowledge, isolated GS of the urinary bladder has been previously reported three times in the literature occurring in early adulthood into middle age. Herein we report the case of a 44 year old female with a 9 month history of intermittent hematuria, dysuria and a pressure sensation in her hypogastrium which was found to be GS of the bladder. The patient had no constitutional symptoms and the rest of the systems review was negative. She had a 7.5 pack-year smoking history and no family history of malignancy. Physical examination was unremarkable except for an obese female with an irregularly irregular pulse and bilateral varicose veins. No lymphadenopathy was noted. A complete blood count was unremarkable. A CT of the pelvis showed a bladder mass for which was biopsied by cystocopy. Histological analyses of the mass revealed a high-grade malignant neoplasm with ulceration and necrosis. Immunohistochemical analyses were positive for both myeloperoxidase and CD117 which, in addition to the morphologic features of the lesion, were suggestive of a granulocytic sarcoma (acute myeloid leukemia). Peripheral blood smear, bone marrow aspirate and bone marrow biopsy showed no abnormalities. Resection of the mass was carried out in addition to induction chemotherapy. Repeat cystoscopy showed mild erythyma of the posterior bladder wall with no evidence of bladder masses, tumors, nodules, lesions or stones. The patient is currently in remission, 6 months after initial diagnosis of graulocytic sarcoma of the bladder.