Cystic benign tumors of the pancreas are rare lesions: they represent less than 10% of all pancreatic neoplasms. We studied two cases of microcystic adenoma, one of the less common varieties, that only in the last few years has been morphologically recognized as a distinct pathological entity. Our clinical experience--though limited--made us remark some interesting features: 1) preoperative diagnostic procedures (ultrasonography and CT) may present great interpretative difficulties: in one of the cases observed, radiographic imaging demonstrated an unresectable pancreatic tumor. On the contrary, in both cases surgical radicality has been achieved; 2) preoperative needle aspiration cytology (FNAB) does not always provide diagnostic material, as happened in both case observed; 3) the diagnosis of a benign tumor may result from surgical exploration and multiple biopsies with intraoperative frozen sections. Further and more complex histological investigations will definitively diagnose a microcystic adenoma; 4) in disagreement with some authors' results, we observed that microcystic adenoma may grow rapidly: one of our patients, after an incomplete tumor enucleation, developed a local relapse in a few months, needing a subtotal distal pancreatectomy, followed by complete recovery; 5) surgical radicality is mandatory. This result can be achieved through a simple, but complete, tumor enucleation or through a pancreatic resection; 6) our immunohistochemical and ultrastructural studies on microcystic adenoma exhibited no cells with endocrine activity, supporting the hypothesis that this tumor may originate from ductal or centroacinar cells.