Abstract: Objective:To study the clinicopathological characteristics, diagnosis, multiple modality therapy and progno -sis of accessory breast cancer. Methods:Clinical data of 38patients with accessory breast cancer seen in our hospital be-tween October 1985and November 2007. Results:The 38cases of accessory breast cancer accounted for 0.15% of all26, 078 breast cancer cases during the same period. Six patients of stage Ⅰand 3 patients of stage Ⅱunderwent breast con -serving local wide excision of the tumor plus axillary lymph node dissection, with the resection margins pathologically nega-tive. The other 9 cases of stage Ⅱpatients were treated with Auchincloss mastectomy. Stage Ⅲand stage Ⅳpatients were treated with Auchincloss or Halsted mastectomy. The most common histological type of accessory breast cancer was infiltrating ductal carcinoma for 18patients (47.4% ), of which 3 cases were associated with adenoma of the nipple tube. There were6 cases of carcinoma simplex, 6 cases of intraductal carcinoma,3 cases of adenocarcinoma with focal squa -mous cancer cells differentiation, 3 cases of medullary carcinoma, and 2 cases of mucinous adenocarcinoma. The most common pathological stages (according to AJCC staging of breast cancer, 2002, 6th edition) were stage Ⅱand Ⅲin 12 cases (31.6%), stageⅠin 6 cases, and stage Ⅳin 8 cases. All patients were followed-up for 1 to 23years. The median fol -low-up time was 6 years and 7 months, and the follow-up rate was 100 %. Until November2008, 12patients died of metas -tasis and the other 26patients were still alive. The 5-year overall survival rate was 35.3%, significantly lower than that of breast cancer patients ( 66.8%). The3-year survival rate was 77.8%. The5-year disease free survival rate was 28.6% and the 3-year disease free survival rate was 63.6%. Conclusion:Accessory breast cancer is rarely seen but is aggressive. The diagnosis mainly depends on clinical characteristics, postoperative pathology and imaging examinations. Early diagnosis is essential. Surgery combined with other adjuvant therapies can improve patient survival.