ObjectiveTo determine the optimal cutoff value of carcinoembryonic antigen（CEA） and amylase in cyst fluid for mucinous cystic neoplasm， to explore the difference of cutoff value of CEA between Chinese and western populations and the diagnostic accuracy of CEA combined with amylase for mucinous pancreatic cysts. MethodsA total of 116 patients received EUS-FNA in Chinese PLA General Hospital from April 2014 to May 2016 with cyst fluid for biochemical and histological examinations and biopsy for pathological examination. The optimal value of amylase and CEA for mucinous pancreatic cysts were obtained from receiver operator characteristics curve of CEA and amylase. The accuracy， sensitivity and specificity of CEA， amylase and combination of both were calculated. ResultsDiagnosis of 70 patients were confirmed by surgery，forceps or cytology. There were 32 cases of non-mucinous pancreatic cysts including 6 pseudocysts and 26 serous cystadenoma. There were 38 cases of mucinous pancreatic cysts including 31 mucinous cystic neoplasm and 7 intraductal papillary mucinous neoplasm. The optimal cutoff of CEA was 72.35 ng／mL. The accuracy， sensitivity and specificity were 84.3％， 81.6％ and 87.5％ respectively. The accuracy, sensitivity and specificity for mucinous cystic neoplasm were 80.0%, 71.1% and 90.6% respectively when adopting CEA＞192 ng/mL. The optimal cutoff of amylase was 461.70 IU／L， and accuracy， sensitivity and specificity were 57.1％， 68.4％， 43.8％ respectively. Combination of CEA＞72.35 ng／mL and amylase＜461.7 IU／L yielded higher accuracy （85.7％） and specificity （93.8％） with lower sensitivity （78.9％）. ConclusionCEA can be used in the differential diagnosis of mucinous and non-mucinous pancreatic cysts. The optimal cutoff of CEA in Chinese was lower than that in western populations. And the combined analysis of CEA and amylase could increase the diagnostic accuracy. However， in order to confirm this conclusion， a study of larger scale is needed.