Little is known about the frequency of germ-line mutations in the breast cancer susceptibility genes BRCA1 and BRCA2 among Asian populations. We investigated the distribution of BRCA1 and BRCA2 germ-line mutations and polymorphisms in a cohort of women from Shanghai, China. Study subjects totaled 1306, and included 645 women with breast cancer, 342 women with benign breast disease, and 319 unaffected controls, born between 1924 and 1958, selected from women enrolled in a randomized trial of Breast Self-Examination in Shanghai, China. Women were selected without regard to family history of breast or ovarian cancer. All of the coding regions and exon-intron boundaries were screened. Data were analyzed with respect to age at diagnosis, and family history of breast and ovarian cancer. The prevalence of known disease-associated mutations in women with breast cancer was 1.1% each, for BRCA1 and BRCA2. Among breast cancer cases with a family history of breast or ovarian cancer, 8.1% and 2.7% carried likely BRCA1 and BRCA2 disease-associated mutations, respectively. Overall, these results suggest that inherited susceptibility to breast cancer due to germ-line BRCA1/2 mutations among women with a family history of breast cancer is comparable between women from Shanghai and Caucasian women of Western European descent. Most alterations observed appear unique to the Chinese population, suggesting a resource that will be useful for assessing risk among both Chinese women and United States women of Chinese descent.