Objective:To analyze the features of clinical diagnosis and treatment of small cell neuroendocrine carcinoma of the breast. Methods:Three cases of breast small cell neuroendocrine carcinoma were admitted between January 2001 and June 2006 in Peking University School of Oncology.Their clinical and pathological data,treatment and prognosis were analyzed retrospectively. Results:All the three lesions were palpable and were found by the patients themselves. Mammography showed no calcification in any of the three lesions.Breastconserving surgery was performed in 2 patients,and modified radical mastectomy in 1 patient. All the patients were diagnosed small cell neuroendocrine carcinoma pathologically. Immunohistochemical results showed Syn（++） and CgA（++） in 2 patients and NSE (+) in 1 patient.Expression of ER,PR and Her2 were negative in all patients.Followup ranged from 9 to 74 months.One patient with no lymph node metastasis was still alive without relapse and metastasis 74 months after the treatment.Multiple metastasis were revealed in 2 patients with lymph node metastasis within 12 months after diagnosis.One died within 15 months after excision.The other had survived for 9 months after excision. Conclusion:Small cell neuroendocrine carcinoma is rare neoplasms of the breast.No calcification and negative expression of ER,PR and Her2 might be the characteristics of the disease.Diagnosis of the disease should depend on pathological results.Significant differences of prognosis and curative effect of treatments suggest that the disease may have subtypes.