Endoscopic ultrasound (EUS) and intraductal ultrasound (IDUS) play very important roles in the field of biliary tract disease. Because of their excellent spatial resolution, the detection of small lesions and T-staging of tumors have become possible. Additionally, contrast-enhanced EUS and the new imaging technique of detective flow imaging are reported to be useful for differential diagnosis. Furthermore, EUS-guided tissue acquisition is used not only for pathological diagnosis, but also to collect tissue samples for cancer genome profiling. Although percutaneous transhepatic biliary drainage (PTBD) was traditionally performed in cases where endoscopic retrograde cholangiopancreatography is not feasible, treatments using EUS have recently become increasingly common, and EUS-guided biliary drainage was recently suggested to be superior to PTBD in terms of a higher success rate, less adverse events, and lower reintervention rate. This review provides an overview of diagnosis and treatment utilizing the features and techniques of EUS and IDUS.