A 60-year-old Turkish woman presented with a left breast mass, which was considered for neoadjuvant chemotherapy. By the end of the treatment cycles, the tumor had decreased in size, and the patient underwent modified radical mastectomy with axillary lymph node dissection. Pathologic examination of the tumor revealed a small cell carcinoma with neuroendocrine features confirmed by immunohistochemical stains. Multiple axillary lymph nodes were involved by metastatic small cell carcinoma carrying the same morphologic characteristics noted in the primary breast tumor. We hereby present this case as a primary neuroendocrine small cell carcinoma of the breast. This entity occurs very rarely in the breast, and fewer than a dozen cases have been reported in the literature. Extrapulmonary small cell carcinoma of the breast is reportedly a very aggressive tumor for which no consensus for treatment has yet been drawn.