Objective To analyze the clinical and ultrasonographic imaging features of intraductal papillary mucinous neoplasm (IPMN) of the pancreas.Methods Twelve patients with IPMN underwent surgery between May 2005 and December 2008, including 4 (33.3%) with adenoma and 8 (66.7%) with adenocarcinoma. IPMN was classified preoperatively into 3 types based on sonographic findings of different sites: main duct, branch duct, and combined type. All clinical presentations and ultrasonographic findings of those patients were reviewed and the correlation be-tween ultrasonographic findings and histopathological results was analyzed.Results There were 9 men and 3 women with a mean age of 60.1±9.6 years (range, 32-73). Of all the 12 patients with IPMN, 9 (75.0%) had experienced some symptoms of epigastric discomfort and/or pain as well as backache; 7 cases were with medical history of acute pancreatitis, 5 cases with diabetes, 4 cases with elevated CAi9-9, and 2 cases with steatorrhea. All lesions of IPMN have been revealed by transabdominal ul-trasonography. The mean diameters of the lesions were 1.4±0.8 cm (range, 0. 5-2.0) and 6.3±6.0 cm (range, 2.0-20.0) in adenomas and adenocarcinomas, respectively. And the mean diameters of the main duct in ade-nomas and adenocarcinomas were 1.0±0.8 cm and 1.6±1.0 cm, respectively. Among the 4 adnomas, 3 (75.0%) cases were classified as branch type based on sonographic findings, and 2 were demonstrated as mural nodules in which no color signals was detected. Among the 8 adenocarcinomas, 5 (62.5%) cases were classi-fied as main duct type, and 3 (37.5%) as combined type. In 7 of the 8 adenocarcinomas, mural nodules were detected within the dilated ducts or cysts of the lesions in which color flow signals were detected.Conclusions Transabdominal ultrasonography can reveal the pancreatic cystic lesions of IPMN as well as dilated pancreatic ducts. Some characteristics should be noticed as suggesting the possibility of malig-nancy: clinical symptoms of pancreatic insufficiency, large tumor size, and mural nodules with color Doppler flow signals. Transabdominal ultrasonography could be a useful tool to help diagnose and make appropriate management of IPMN.