Recent studies suggested that breast cancer patients who carry a BRCA1 germline mutation benefit from poly (ADP-ribose) polymerase (PARP) inhibitors; therefore, it would be of great interest to detect BRCA1 somatic mutations in sporadic breast cancers. In this study, we detected BRCA1 somatic mutations in tumor cDNA from 144 Chinese women with sporadic breast cancer by using polymerase chain reaction (PCR)-direct sequencing assay. In total, eight BRCA1 alterations (three nonsense mutations and five missense mutations) were identified in this cohort of 144 sporadic breast cancers. We further confirmed that 5 out of 144(3.5%) sporadic breast cancer cases carried a BRCA1 somatic mutation, including two novel nonsense mutations (c.191_212del22 and c.2963C>G) resulting in a truncated protein and three missense mutations (c.114G>T, c.925A>C, and c.824G>A). The two cases with BRCA1 somatic truncating mutations also contained a TP53 somatic mutation in the tumors. Our study suggested that a small subset of sporadic breast cancers do harbor BRCA1 somatic mutations; these patients who carry a BRCA1 somatic mutation may be potential candidates for treatment with PARP inhibitors.