Abstract: Objective: To analyze the differential expression of proteins in the pancreatic juice of patients with pan-creatic cancer (pc), chronic pancreatitis (cp) and choledocholithiasis by methods of proteomics. Methods: pancreatic juicewas collected by naso-pancreatic drainage during endoscopic retrograde cholangiopancreatography. The total proteins ofpooled pancreatic juice (200ug) with equal amount from five pc patients, six cp patients and three choledocholithiasis pa-tients were separated by two-dimensional gel electrophoresis(2-DE) respectively. The expression of proteins were analyzedby image analysis software and identified by mass spectrometry and database searching. Results: 1) Pancreatic juice wassuccessfully collected by naso-pancreatic drainage during endoscopic retrograde cholangiopancreatography with amountranging from 35 to 200 ml and protein concentration ranging from 0.8-4.6μ g/μ l. Three gels of the same pancreatic juice(200ug) had good reproducibility in protein location. Rates of matched proteins from pooled pancreatic juice with equalamount from five pc patients, six cp patients and three choledocholithiasis patients all exceeded 75% by self-contrast. 2)Nine differential proteins obtained from image analysis software were analyzed by MALDI-TOF-MS and some were identi-fied as differential expressed proteins related to pancreatic cancer. Conclusion: Protein spectra of pancreatic juice from pcpatients, cp patients and choledocholithiasis patients are different.