Olaparib was the first poly ADP-ribose polymerase inhibitor approved for patients with cancer with mutations in either or in China. To the best of our knowledge, however, no study has described the efficacy of olaparib for patients with breast cancer with double mutations in and . The present case report describes a patient with breast cancer with deleterious germline mutations in both and . The 56-year-old patient with multiple metastatic breast cancer underwent breast cancer resection with 12 years interval between removal of the left and right breast. Germline mutations in both (S405X) and (W2990X) were identified by NGS. She received two cycles of chemotherapy with a combination of albumin-bound paclitaxel and capecitabine; the response was progressive disease. Subsequently, the patient was treated with a gradual dosage of decreasing olaparib (600 to 300 mg BID) for 6 months until grade 3 anemia could not be alleviated by giving erythropoietin and iron, and CT imaging showed a partial response (35% reduction). The patient then switched to exemestane therapy due to the continuous grade 3 anemia. In conclusion, the present study reported a female patient with double heterozygosity of BRCA1 and BRCA2 who benefited from olaparib monotherapy. Thus, olaparib may be a suitable treatment for such patients.