In a 45-year-old man with acute pancreatitis and recent onset of diabetes mellitus, intraductal papillary mucinous neoplasm (IPMN) associated with pancreas divisum was found. There were no arguments for an invasive component in the IPMN lesions, which seemed to involve nearly all the dorsal pancreas. Resection of only the dorsal pancreas was performed with division of the pancreas at the internal side of the duodenum and at the anterior edge of the common bile duct. The gastroduodenal artery was preserved resulting in good vascularization of both common bile duct and proximal duodenum. Postoperative course was marked by a transient pancreatic fistula. Definitive pathological examination revealed noninvasive IPMN involving several branch ducts and partially the cephalic dorsal duct, with an 8 mm tumor-free segment from the transection level. Twelve months after resection, the patient had normal gastrointestinal function with neither clinical exocrine insufficiency nor uncontrolled diabetes. Postoperative magnetic resonance imaging revealed no signs of recurrence in the ventral pancreas. In patients with pancreas divisum, dorsal pancreatectomy can be proposed for noninvasive IPMN involving only the dorsal pancreas to avoid drawbacks of total duodenopancreatic resection.