Large cell neuroendocrine carcinoma (LCNEC) of the urinary bladder is rare. It is a type of neuroendocrine carcinoma morphologically distinct from small cell carcinoma. We report here a case of primary LCNEC of the urinary bladder. We observed a very large invasive tumor, which was not able to be detected three months previously by cystoscopy or computed tomography. The tumor cells morphologically and immunohistochemically resembled that of pulmonary LCNEC. With prompt cystoprostatectomy and chemotherapy, the patient is free of disease 16 months after diagnosis. Although LCNEC is usually very aggressive, it may be controlled by early diagnosis and treatment.