Introduction: The dilation of the bile ducts which the obstacle could not be visualized by conventional imaging, constitutes a daily challenge in our medical practice. This work aims to evaluate the frequency and the role of biliopancreatic echo-endoscopy in the etiological diagnosis of bile duct dilatation. Material and methods: This is a descriptive and monocentric retrospective study conducted within the department of 'Digestive Functional Explorations and Hepato-gastro-enterology' at the Ibn Sina Hospital in Rabat, from September 2015 to April 2023. It includes 115 patients admitted for dilation of the common bile duct with no visible obstacle to conventional imaging and who underwent a bilio-pancreatic echo-endoscopy. Results: Our study included 81 patients, whose mean age was 61.2 years with a clear female predominance. Echo-endoscopy confirmed the presence of bile duct dilation in 67% of cases. It established an etiological diagnosis in 82% of cases. Lithiasis of the common bile duct was found in 42,9% of cases, followed by cystic dilation in 12,9% of cases and chronic pancreatitis in 5.2% of cases. A pancreatic tumor has been revealed in 3,8% of cases as well as an ampulloma in 3,8% of cases. Conclusion: Our study, despite its limitations, highlight the role and performance of biliopancreatic echoendoscopy in the etiological diagnosis of bile duct dilatation without any visible obstacle to conventional imaging.