The primary purpose is to compare patency of two different types of biliary metal stents, i.e. covered versus uncovered Nitinella metal stent. Secondary purposes are to determine frequency of complications in the two groups, e.g. cholecystitis, pancreatitis, and cholangitis.

Inclusion Criteria:

• 20 years of age or older
• oral and written information given and informed consent obtained
• clinical data in accordance with malignant bile duct obstruction
• ultrasonography signs of extrahepatic malignant common bile duct obstruction
• typical radiological findings at ERCP of malignant common bile duct stenosis
• proximal margin of the bile duct stenosis at least 2 cm from the hepatic confluence
• bilirubin > 50 micromol/L
• radical surgery estimated not possible (temporary stenting with insertion of a plastic stent can be obtained but should be replaced by a metal stent within 4 weeks after the first ERCP procedure, and the patient is randomized at the time of insertion of the metal stent)

Exclusion Criteria:

• patients with active hepatitis or other hepatic diseases that may cause jaundice
• informed consent not obtained
• metastasis with numerous significant intrahepatic stenosis causing blockage of one or more segments of the liver (if no segment blockage, liver metastasis is not an exclusion criteria)
• the patient is probably a candidate for surgical resection
• suspicion of a non-malignant bile duct obstruction, e.g. stones or benign stenosis (should initiate further investigations)
• the proximal end of the stenosis is located within 2 cm from the hepatic confluence
• the patient has previously undergone BII or Roux-en-Y gastric resection, or has a significant duodenal obstruction making ERCP difficult
• previously (more than 4 weeks earlier) treated with a bile duct stent
• severe coagulation disturbance (PK-INR > 1.6)