RATIONALE: Pancreatic acinar cell carcinoma (PACC) is a relatively rare malignancy of the exocrine pancreas. BRCA2, a cancer susceptibility gene, has been widely studied in breast and ovarian carcinomas as mutation carriers for this gene are at a high risk for cancer development. Olaparib, an oral poly(adenosine diphosphate-ribose) polymerase (PARP) inhibitor, has been approved for the treatment of ovarian cancer with any BRCA 1/2 mutations. Herein, we report the first case of a germline BRCA2-mutated unresectable advanced PACC patient who responded well to olaparib treatment. PATIENT CONCERNS: A 59-year-old male with a family history of cancer presented with a persistent epigastric dull pain for 3 months. DIAGNOSIS: The patient was diagnosed with advanced PACC based on computed tomography (CT) scan, laparotomy, and pathology. INTERVENTIONS: Exploratory laparotomy, intratumoral brachytherapy by radioiodine-125 seeds, modified FOLFIRINOX chemotherapy, and targeted therapy with olaparib were administered. OUTCOMES: The patient responded well to olaparib until the occurrence of severe adverse drug reactions, he died as a result of multiple organ failure with an overall survival period of 12 months. LESSONS: As a PARP inhibitor, olaparib has remarkable curative effect not only on breast and ovarian cancers, but also on other malignancies with BRCA mutations. Patients with advanced cancer could benefit from active targeted therapy with improvement in overall survival and quality of life.