Since the late 1970s, endoscopic biliary stenting has become a standard palliative treatment for obstructive jaundice due to malignancies of the pancreas and the hepatobiliary system. Despite the high initial success rate in achieving biliary drainage, endoscopic stenting therapy has been limited by the clogging of biliary stents, usually after four to five months, due to formation of adherent bacterial biofilm and accumulation of biliary sludge. Various methods for the prevention of bacterial adhesion and prolongation of stent patency have been investigated, including prophylactic antimicrobial agents and bile salts, new stent materials, and new stent designs. Recently, the introduction of self-expandable metal stents has significantly improved the duration of stent patency but the cost is considerably higher. Each method has its own merits as well as specific problems. This article reviews the pathogenesis of biofilm formation on the biliary stents and the latest status of research in avoiding stent occlusion.