During the last two decades, intraductal papillary-mucinous neoplasms have been recognised as a group that should be distinguished from ductal adenocarcinomas. The literature for these tumors is confusing with the use of many different terms such as mucinous duct ectasia and, sometimes, there is a failure to distinguish them from mucinous cystic tumors. The recognition and apparently increasing incidence of these neoplasms is perhaps entirely attributable to improved diagnostic and imaging methods such as endoscopic retrograde pancreatography and computerized tomography. Experimental, molecular, and epidemiologic data suggest that the etiology of IPMN overlaps that of solid ductal adenocarcinomas.