Chronic pancreatitis (CP) is a pancreatic disease with poor prognosis characterized clinically by abdominal pain, morphologically by pancreatic stones/calcification, duct dilatation and atrophy, and functionally by pancreatic exocrine and endocrine insufficiency. CP is also known as a risk factor for the development of pancreatic cancer. CP has long been understood based on a fixed disease concept deduced from the clinical and morphological features of the end-stage disease. However, identification of causal genes for hereditary pancreatitis and success in the isolation and culture of pancreatic stellate cells have advanced the understanding of the underlying pathological mechanisms, the early-stage pathophysiology, and the mechanisms behind pancreatic fibrosis. These advances have led to moves aimed at improving patient prognosis through prevention of disease progression by early diagnosis and early therapeutic intervention. The strategy for preventing disease progression has included a proposal for diagnostic criteria for early CP and introduction of a new definition of CP in consideration of the pathological mechanisms. Our group has been committed deeply to these studies and has provided a large amount of information to the world.