Endoscopic aspiration of pure pancreatic juice (ppj) was performed on 65 patients with chronic pancreatitis (cp) or suspected CP primarily for evaluating the validity of biochemical and physiochemical analysis of PPJ in the study of pathogenesis, pathophysiology and diagnosis of CP. PPJ was collected from within the main pancreatic duct by endoscopic retrograde catheterization of the papilla. With increasing experience, it has been revealed that various numbers of protein plugs are contained in PPJ obteined from patients with CP or suspected CP and that endoscopic elimination of protein plugs can provide them with dramatic relief from abdominal pain and back pain. The purpose of this report is to evaluate the role of endoscopic elimination of protein plugs in the treatment of CP. The following conclusions were obteined: (1) endoscopic elimination of protein plugs from within the pancreatic duct is useful. at least on a short-term basis, for relieving abdominal pain and back pain in one-forth of patients with CP or suspected CP; (2) this procedure can be an effective therapeutic tool in selected cases of CP or suspected CP where no prominent stenotic lesions are noted in the major pancreatic duct system and abstinence from alcohol bevarage is strictly observed.