The hepatobiliary surgeon must be as familiar with the nonmalignant processes that can affect the extrahepatic biliary tree as they are with the malignant causes. Subtleties in the patient’s history, presentation, and imaging studies may prevent unnecessary extensive hepatobiliary resection. The focus of this article deals with the etiology of nonmalignant obstruction at the biliary bifurcation and hilum and the mid-bile duct. It does not focus on either choledocholithiasis or pancreatitis, the two most common causes of distal bile duct obstruction. Obstruction from pancreatic cancer is also not the focus of this discussion.