Primary small cell carcinoma of the urinary bladder is an uncommon tumor, compared to the frequency of urothelial tumors. Fifty percent of cases are combined with a non endocrine carcinomatous component. We report six new cases of this tumor, three of pure, and three associated with an urothelial carcinoma. Diagnosis is easy established by the immunohistochemical study which show the neuro-endocrine differentiation of these aggressive tumors. Pathologist needs to look for a neuro-endocrine part in all bladder cancer, as its presence modify the treatment. Chemotherapy is used in these cancers, due to their high metastatic power. Places of radical surgery and radiotherapy need to be specified.