The natural history and clinical manifestation of resected intraductal papillary mucinous neoplasm (IPMN) of the pancreas were elucidated, and based on this, a retrospective pancreatic database was reviewed to identify patients with IPMN who were surgically managed in our department from 1999 to June 2006. Pathologic rereview of each case was performed, and the clinico-pathologic features were examined. Student s test and analysis were used to identify factors associated with malignancy. Fifty-one patients were identified. There were 33 males and 18 females. One patient s pancreas was unresectable, two patients underwent a total pancreatectomy, 42 patients had a pancreatecoduodenectomy and five patients had distal pancreatectomy. Main-duct type carcinoma was identified in 24 patients; branch-duct type in 15 patients, and mixed type in 12 patients. Invasive carcinoma was present in 35 patients. Weight loss and jaundice occurred more commonly in the invasive group. The average serum CA19-9 level was significantly higher in the invasive group (1542μ 94.5μ). The average diameter of the pancreatic duct was also wider in the invasive group (8.7 mm 4.3 mm). Significant predictors of malignant IPMNs included weight loss, jaundice, a high level of serum CA19-9, a large pancreatic duct and main-duct type carcinoma.