BACKGROUD: Women with unilateral breast cancer are at increased risk for developing contralateral disease. The objective of the single-center retrospective study was to evaluate the incidence of bilateral breast cancer (BBC) and to analyze the clinicopathological characteristics for BBC in China. METHODS: We retrospectively reviewed the electronic medical records of 3924 female patients with breast cancer consecutively treated at the department of Breast Oncology in the Peking University Cancer Hospital between 2006 and 2016. BBC was categorized as synchronous (within 6 months) or metachronous bilateral breast cancer (after 6 months of a first tumor). Patients with BBC were identified according to the criteria described by Chaudary et al. Patients with stage IV first breast cancer, and those who were found to have distant metastases between the first and second primary breast cancer were excluded. Analyses of demographic, clinicopathologic, and treatment characteristics were done between sBBC and mBBC. RESULTS: The incidence of BBC in our population was 3.2% (127 of 3924). Of those, 2.5 % ( 99 of 3924) were metachronous bilateral breast cancer ( mBBC ), and 0.71 % (28 of 3924) were synchronous bilateral breast cancer ( sBBC ). The overall median age of the patients at first diagnosis was 45 years (range, 27-81 years). The age of onset of the first mBBC was significantly younger than that of sBBC ( p = 0.027). In mBBC subgroups, the median time interval between first and second tumors was 68 months (range, 7-342 months), and 80.8% of the second tumor were diagnosed within 10 years of the diagnosis of the first tumor. A positive family history of breast cancer was found in 25% of sBBC and 9.1% of mBBC ( p = 0.025). In ER-negative first tumor of mBBC, 56.1% of the second tumor were ER-positive. Mastectomy was the commonest surgery performed in these patients. CONCLUSIONS: Our results confirmed the necessity of screening contralateral breast at the diagnosis of unilateral breast cancer and following-up for Chinese patients with breast cancer. Citation Format: Li H, Jiang H, Zhang R, Shao B, Yan Y, Ran R, Di L. Bilateral breast cancer in China: A 10-year single-center retrospective study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-10-13.