Abstract. Primary small cell carcinoma of the breast is a rare tumor of which less than 40 cases have been reported in the literature. Because of its rarity, its biological and clinical characteristics are still not fully understood and, to date, no standard therapy has been developed. Here, we present a case and a review of the literature regarding this cancer, focusing on clinicopathological findings and treatment. Primary small cell carcinoma of the breast differs from more common types of breast cancer in its biological features. It is anticipated that an improved understanding of the clinical characteristics of this tumor will result in the development of new therapeutic modalities, which would improve its prognosis.