A widely used classification of pancreatitis is the one proposed in Marseilles in 1963, which distinguishes among acute, acute relapsing, chronic relapsing, and chronic pancreatitis. The diagnostic criteria in chronic pancreatitis are permanent damage of morphology and/or function of the pancreas after clinical symptoms of pancreatitis. In clinical practice, however, it can be difficult to find the suitable and comparable diagnosis in accordance with the Marseilles classification. In the present study the exocrine and endocrine function and the morphology of the pancreas have been thoroughly investigated in 54 patients who have been treated for various diagnoses of pancreatitis. The results show that the above diagnostic criteria often are difficult to interpret. We consider that the prevailing classification of pancreatitis needs to be revised in the light of progress in investigative techniques. A proposal for a modified classification is presented.