Introduction In patients with a biliary obstruction, tissue is acquired immediately before drainage during endoscopic retrograde cholangio-pancreatography (ERCP). This is performed by passing a brush inside the bile duct stricture. However, brush cytology has a modest sensitivity (30-57%) for the diagnosis of cancer. A device, called the "G.I.U.M." catheter, allows for the sampling of higher amounts of tissue during ERCP compared to brush cytology. The aim of this study is to compare the diagnostic yield of tissue sampling performed in patients with a suspected malignant biliary stricture using 2 techniques, namely a standard brush catheter and the G.I.U.M..