The authors present differential diagnosis of parasitic invasion of the common bile duct. A 52-year-old patient admitted with malignant bile duct obstruction, mechanical jaundice, cholestatic hepatitis and cholangitis. Bile duct tumor was preliminary diagnosed according to anamnesis, complaints, physical, laboratory and instrumental data. Retrograde cholangiopancreatography, endoscopic papillotomy and revision of the common bile duct were performed. There was occlusion at the level of the upper third of the common bile duct. Retrograde cholangioscopy was performed to clarify the nature of obstruction and tumor. Cholangioscopy revealed parasites in the common bile duct that required extraction. The patient was sent to the infectious disease hospital.