On 1997, the Digestive Endoscopy Centre of "Arzobispo Loayza" Hospital was created with the cooperation of JICA (Japan International Cooperation Agency). 902 ERCP were regularly performed from 1985 to August 1997. 902 tests were reviewed and 831 cases were left after excluding 16 ampulloma cases, 15 cannulated or insufficient cases and 40 cases dealing only with pancreatic duct cannulation. The population is examined according to sex, age and diagnosis, establishing a relation among these three variables. Results showed that most of ERCP were made to women (3:1) with Choledocal Lithiasis (C.L.) and cholecistectomy antecedents, a greater frequency was observed in 56-65 year old women. In males, it was more frequent in people older than 65 years, they also had predominance of choledocal lithiasis, but malignant neoplasia of the biliary duct ranked in the third place. The highest incidence of C.L. with cholecistectomy antecedents suggests the performance of an appropriate evaluation of the biliary duct before surgery.