Neuroendocrine tumors are very rare tumors that occur most commonly in the gastrointestinal tract. The occurrence of neuroendocrine tumors outside gastrointestinal tract is very rare but not unknown. Thus, neuroendocrine tumors and their primary seat can be found in the bronchi and lungs, as well as in the testicles, ovaries, prostate, etc. The occurrence of neuroendocrine tumors as a primary seat in the breast is extremely rare phenomenon that is described in literature. We present the case of 55-year old female in where routine mammographic examination found suspicious lesions that we recommended for further processing. The patient made a breast ultrasound examination in which tumor formation was found in size 27 x 19 mm and cytological puncture found breast adenocarcinoma. Further pathohystologic and immunohistochemical analysis set the diagnosis of neuroendocrine carcinoma, small cell type, second grade. Tumor formation by ultrasound initially sized 27 x 19 mm and pathohistologic diagnosis showed tumor size 26 x 20 x 20 mm. The axillary lymph node biopsy did not found distant metastases in lymph nodes as well as gatherings in other organs. Neuroendocrine small cell carcinomas are exceedingly rare phenomena in the literature. By the year 2009 in the USA there were described only 50 cases of this extremely rare tumor of the breast.