Cystic tumors of the pancreas have become increasingly prevalent. In large series, more than 90% of pancreatic cystic neoplasms are accounted for by mucinous cystadenomas and cystadenocarcinomas, serous cystadenomas, and intraductal papillary mucinous tumors. Differentiating cystic neoplasms from pseudocysts can almost always be accomplished by clinical and radiological means, but in doubtful cases, when observation is contemplated, or when it is important to determine preoperatively the type of cystic neoplasm, cyst fluid analysis is useful. This can be readily obtained by endoscopic ultrasound, and analysis of enzymes, viscosity, cytology and a variety of tumor markers allows for a better differential diagnosis.