Peroral cholangioscopy has been used since the 1970'es and provides direct visualization of the biliary tree, possibility of electrohydraulic or laser lithotripsy and visually guided biopsies. This paper presents an overview of the existing literature focusing on the Spyglass single-operator cholangioscopy system. Several studies indicate that cholangioscopy can improve therapy of difficult accessible biliary stones and histological diagnosis in patients with indeterminate bile duct stenoses.