Stenting the malignant biliary obstruction is considered to be the preferred palliation modality to relieve pruritus,cholangitis,pain and jaundice in patients without surgical indications of malignant biliary obstruction.An unicentral clinical trial has demonstrated the safety and technical feasibility of an irradiation biliary stent insertion in patients with biliary obstruction caused by adenocarcinomas, such a treatment seems have benefits in relieving jaundice and extending survival when compared to a conventional biliary stent.However,the small sample size,the population distribution of two groups will influence the final results in obtaining a powerful statistical conclusion.Therefore,a multicentric study was designed to prospectively compared the responses to the treatment with this irradiation biliary stent versus the conventional biliary self-expandable stent in patients with inoperable malignant biliary obstruction.