Studies of ERCP-related morbidity seldom include a sufficient patient follow -up. The aim of this study was to characterize and to evaluate the frequency of complications, cardiopulmonary untoward events in particular. All patients unde rgoing ERCP during a 2-year period were included in this prospective study. Com plications were assessed at the time of ERCP and by postal/telephone contact at 30-days after the procedure. A total of 1177 ERCPs were included in the analysis, of which 56.2%were therapeutic. The 30-day complication rate was 15.9%; the procedure-related mortality rate was 1.0%. Post-ERCP pancreatitis occurred in 3.8% of patients (3 deaths). Hemorrhage or perforation occurred with 0.9% and 1.1%, respectively, of the procedures (3 deaths). One perforation that resulted in the death of the patient occurred after placement of an endoprosthesis. Cholangitis occurred in relation to 5% of the ERCP procedures (3 deaths). Cardiores piratory complications occurred in 2.3%(2 deaths). Dilated bile duct (p = 0.000 1), placement of stent (p = 0.001), and use of more than 40 mg of hyoscine-N-butyl bromide (p < 0.05) were risk factors for complications by multivariate analysis. Risk of pancreatitis was increased with age under 40 years (p = 0.0078), placement of stent (p = 0.031), and a dilated bile duct (p = 0.036). This prospec tive study confirms that the complication rate of ERCP including therapeutic pro cedures is high. Cardiopulmonary complications were not as common as expected, despite being the special focus of the study. Studies of ERCP-related morbidity seldom include a sufficient patient follow -up. The aim of this study was to characterize and to evaluate the frequency of complications, cardiopulmonary untoward events in particular. All patients unde rgoing during ERCP during a 2-year period were included in this prospective study. Com plications were assessed at the time of ERCP and by postal / telephone contact at 30-days after the procedure. A total of 1177 ERCPs were included in the analysis, of which 56.2% were therapeutic. The 30-day The procedure-related mortality rate was 15.9%; the procedure-related mortality rate was 1.0%. the procedure-related mortality rate was 1.0%. the procedure-related mortality rate was 1.0%. the procedure-related mortality rate was 1.0% ) One perforation that resulted in the death of the patient occurred after placement of an endoprosthesis. Cholangitis occurred in relation to 5% of the ERCP procedures (3 deaths). Cardiores heart hospitalization occurred in 2.3% (2 deaths). Dilated bile duct (p = 0.0001), placement of stent (p = 0.001), and use of more than 40 mg of hyoscine-N-butyl bromide (p <0.05) were risk factors for complications by multivariate analysis. This prospec tive study confirms that the complication rate of ERCP including therapeutic pro cedures is high (p = 0.0078), placement of stent (p = 0.031), and a dilated bile duct Cardiopulmonary diseases were not as common as expected, despite being the special focus of the study.