Primary pure small cell carcinoma of the urinary bladder is an extremely rare and highly aggressive tumor with an average five-year survival rate of less than 10% as cited by multiple case reports. It accounts for about 0.5-1% of all bladder tumors. We present the case of a 44-years-old man, smoker (10 cigarettes/day) hospitalized in the Department of Urology, from the "Prof. dr. Th. Burghele" Hospital, Bucharest, for one month intermittent hematuria. Ultrasonography showed a sessile tumoral mass, sized 37/30mm. Transurethral resection of the tumor mass was performed and tissue fragments were sent to the pathologic lab to establish the histologic type, the degree of differentiation and invasion. Fragments of the tumor were fixed in 10% formaldehyde, paraffin embedded and processed as standard technique; the sections were stained with HE, VG and immunohistochemically with: CROMO, EMA, NSE, CD56, NK1, p53 and betaHCG. The microscopic examination reveled a tumor proliferation composed of two distinct components: extensive small cells areas and foci of typical low grade (G2) papillary urothelial carcinoma. The small cell are uniformly, round, with increased nucleo-cytoplasmic ratio, eosinophyl cytoplasm, hyperchromatic nuclei, finely granular chromatin and inconspicuous nucleoli. Immunohistochemical stains showed diffuse positive staining of the small cell component for CROMO, EMA, NSE, CD56, NK1 and urothelial carcinoma component stained focally for betaHCG. The rate of cell proliferation was increased (p53 - 80% positive reaction). Conclusions. A diagnosis of small cell carcinoma coexisting with low-grade urothelial carcinoma was established. Because of aggressive behavior and distinct treatment, the pathologist should watch out for the presence of small cell carcinoma component.