Chronic pancreatitis was not a clinical entity until around 1960 in Japanese gastroenterology. The diagnosis of chronic pancreatitis had been vague and difficult to ascertain. The diagnostic criteria for chronic pancreatitis were first proposed in 1971, and they were subsequently revised in 1983. Patient numbers of chronic pancreatitis were summed by national surveys under each of the common diagnostic criteria. Total patient number and incidence rate of chronic pancreatitis are recognized as increasing throughout Japan, based on results of two national surveys of chronic pancreatitis. The diagnostic criteria for chronic pancreatitis in Japan were again revised in 1995, because the 1983 criteria were too complicated, and there had been more recent progress in clinical investigations of the pancreas. The essential revised points of the Diagnostic Criteria, 1995, are introduced in this review along with some discussion.