Objective：To investigate the expression of protein MUC1 and MUC2 in intraductal papillary mucinous neoplasms (IPMNs) and its significance.Methods: Immunohistochemical method (EnVision) was used to analyze the expression of protein MUC1 and MUC2 in 18 IPMNs and 9 pancreatic ductal adenocarcinomas.Results: Expression of protein MUC1 was detected in 4 of the 18 (22%) IPMNs (including 1 with pancreatic intraductal papillary-mucinous carcinoma) and all the 9 (100%) the pancreatic ductal adenocarcinomas,with the latter significantly higher than the former(P<0.01).Expression of protein MUC2 was detected in 17 of the 18 (94.4%) IPMNs and in 1 of the 9 (11.1%) pancreatic ductal adenocarcinomas,with the former significantly higher than the latter(P<0.01).The expression levels of MUC2 were significantly different in IPMNs of different types (IPMA,IPMB,and IPMC,P＜0.05).Conclusion: IPMNs have high expression of MUC2 and the expression is associated with the pathological types of IPMN.MUC1 expression may serve as a marker of malignant IPMNs and is worth further studying.