Vascular complications in chronic pancreatitis are not common, but once they occur they may be life-threatening and difficult to treat. There is a lack of classification that would help us to identify these patients at risk who may benefit from timely intervention and adequate treatment. The aim of the study is to analyze this question and to present a classification system of vascular complications in chronic pancreatitis. 154 patients with chronic pancreatitis treated during the 15-year period 1977-1992 were analyzed in this study. 73 patients treated before 1986 have been analyzed retrospectively. The remaining 81 patients were studied prospectively according to a defined protocol. 72 vascular lesions occurred in 46 of the 154 patients (30%). 21 patients had ‘nonbleeding’ (group I) vascular complications mainly due to venous thrombosis or compression. 25 patients suffered from bleeding complications (group II) and were further divided into ‘nonpancreatic’ versus ‘pancreatic’ bleeding subgroups. Comparing morbidity and mortality in group I and group II, we found a low morbidity and a zero mortality in group I as compared with a 32% morbidity and a 24% mortality in group II. Further comparing the ‘nonpancreatic’ and the ‘pancreatic’ bleeding subgroups, ‘nonpancreatic’ bleeders showed low morbidity and mortality as compared with a 50% morbidity and a 50% mortality in the ‘pancreatic’ bleeder subgroup. Indeed, 83% of all deaths with vascular complications occurred in this ‘pancreatic’ bleeder subgroup. Pancreatic bleedings also showed a high coincidence with pancreatic pseudocyst formation and fistula formation. This proposed classification concept of vascular lesions in chronic pancreatitis enables the detection of truly high-risk patients for severe complications and, therefore, those who may benefit from timely intervention before a potential life-