AIM: As intraductal papillary mucinous neoplasm (IPMN) has a favorable prognosis, associated malignancies have potential significance in these patients. We examined the incidence and characteristics of pre-existing, coexisting and subsequent malignancies in patients with IPMN. METHODS: Seventy-nine cases of IPMN were diagnosed by detection of mucous in the pancreatic duct during endoscopic retrograde pancreatography. Histological diagnosis was confirmed in 30 cases (adenoma (n=19) and adenocarcinoma (n =11). Other primary malignancies associated with IPMN, occurring in the prediagnostic or postdiagnostic period, were investigated. Postdiagnostic follow-up period was 3.3±0.5 years (range, 0.2-20 years). RESULTS: Other 40 malignancies occurred in 28 patients (35%). They were found before(n=15), at (n=19) and after (n=6) the diagnosis of IPMT. Major associated malignancies were gastric cancer (n=12), colonic cancer (n=7), esophageal cancer (n=4), pulmonary cancer (n=4), and independent pancreatic cancer (n=3). Pancreatic cancer was synchronous with IPMN in two patients and metachronous in one (3 years after diagnosis of IPMN). Thirty-one lesions were treated surgically or endoscopically. Fourteen patients died of associated cancers. Development of other malignancies was related to age (71.9±8.2 vs66.8±9.3, P<0.05), but not to gender or site of the tumor. CONCLUSION: IPMN is associated with a high incidence of other malignancies, particularly gastric and colonic cancers. Common genetic mechanisms between IPMN and other associated malignancies might be present. Clinicians should pay attention to the possibility of associated malignancies in preoperative screening and follow-up of patients with IPMN. AIM: Aspastductal papillary mucinous neoplasm (IPMN) has a favorable prognosis, associated malignancies have potential significance in these patients. We examined the incidence and characteristics of pre-existing, coexisting and subsequent malignancies in patients with IPMN. METHODS: Seventy-nine cases of IPMN were diagnosed by detection of mucous in the pancreatic duct during endoscopic retrograde pancreatography. Histological diagnosis was confirmed in 30 cases (adenoma (n = 19) and adenocarcinoma (n = 11). Other primary malignancies associated with IPMN, occurring in the prediagnostic Postdiagnostic follow-up period was 3.3 ± 0.5 years (range, 0.2-20 years). RESULTS: Other 40 malignancies occurred in 28 patients (35%). They were found before (n = 15), at n = 19 and after (n = 6) the diagnosis of IPMT. Major associated malignancies were gastric cancer (n = 12), colonic cancer (n = 7), esophageal cancer = 4), and independent p ancreatic cancer (n = 3). Pancreatic cancer was synchronous with IPMN in two patients and metachronous in one (3 years after diagnosis of IPMN). Thirty-one lesions were treated surgically or endoscopically. Fourteen patients died of associated cancers. CONCLUSION: IPMN is associated with a high incidence of other malignancies, particularly gastric and colonic cancers. Common genetic mechanisms between IPMN and other associated malignancies might be present. Clinicians should pay attention to the possibility of associated malignancies in preoperative screening and follow-up of patients with IPMN.