Background: Any carcinoma of prostatic origin which is not an acinary adenocarcinoma of the prostate is considered to be an atypical carcinoma. One member of this group of atypical prostatic tumors is the oat-cell carcinoma, or small cell carcinoma (SCC) of the prostate. This variety of carcinoma constitutes the histologic basis of <1% of all prostatic neoplasms. Methods: Between 1992 and 1997, four patients were diagnosed with SCC of the prostate at our hospital. In 3 of the 4 cases, the histopathological diagnosis was pure SCC, and in the 4th case there was a component of prostatic adenocarcinoma associated with the SCC. At the time of diagnosis, extracapsular extension of the tumor was present in all 4 cases, with T3 or higher stages in all of them (T3AN₀M1, T3AN₀M₀, T3BN₀M1, and T4N₀M₀). Because of the presence of extracapsular extension, radiotherapy and radical surgery were ruled out for all 4 patients. They were all offered systemic chemotherapy with cyclophosphamide (1 g/m2), doxorubicin (50 mg/m2) and vincristine (1.2 mg/m2). This therapeutic protocol was carried out in only 2 cases. Results: Survival was <1 year in the 3 patients with pure SCC, and the patient with a mixed tumor is alive with detectable disease 9 months after diagnosis. Conclusions: This poor vital prognosis in SCC stresses the need for early diagnosis a timely and appropriate therapeutic intervention in this condition.