The insertion of a biliary endoprosthesis has become standard therapy in the palliative treatment of a malignant biliary stenosis. For plastic stents, stent occlusion results from clogging caused by the adherence of proteins, bacteria, and sludge to the inner stent wall, resulting in a median stent patency of about 4 to 5 months. No major gain in stent patency can be obtained by the omission of side holes, nor by changes in stent material. Putting the stent inside the bile duct, in a suprapapillary position, does not lead to a longer stent patency. The prophylactic administration of antibiotic agents such as ciprofloxacin or norfloxacin, that are active against the gram-negative enterobacteriaceae leading to stent clogging, could have potential advantages but still needs further study. The insertion of a straight 10 French gauge polyethylene Amsterdam-type of prosthesis in a normal transpapillary position, and without the administration of any prophylactic antibiotic treatment, can still be regarded as state-of-the-art therapy with a plastic stent. This mainly holds true for those patients with a low life expectancy of only a few months, such as it is often the case in patients in a poor clinical condition, with liver metastasis, or with a large primary tumor. Patients with a longer life expectancy can be treated with a self-expandable metallic stent. At present, there is no major indication that coated metallic stents will perform any better than the uncoated ones.