We report an unusual case of acinar cell cystadenoma of the pancreas in a 52-year-old man treated for pulmonary adenocarcinoma. The lesion, located in the body of the pancreas, was revealed incidentally by abdominal computed tomography during follow-up for a pulmonary neoplasm. A left pancreatectomy was performed. The unilocular cystic lesion measured 5 cm and was lined by a single layer of columnar acinar cells with eosinophilic granular cytoplasm, faintly stained by periodic acid-Schiff. Immunohistochemical analysis showed the lining cells were positive for cytokeratin and trypsin, and electronic microscopy showed that they contained zymogen granules. Acinar cell tumors of the pancreas are rare and include acinar cell carcinomas, acinar cell cystadenocarcinomas, and acinar cell adenomas. We report a case of cystic acinar cell tumor of the pancreas with benign gross and histologic features that could be added to the list of cystic neoplasms of the pancreas as acinar cell cystadenoma.