Serum Carbohydrate Antigen, CA19-9, is a carbohydrate antigen whose usage -as a tumor marker- in pancreatic and bile ducts malignancies is commonly increasing. Sensitivity and specificity of this antigen in the diagnosis of malignancies is 70-90% and 68-91%, respectively. CA19-9 can also rise in other disorders and in few of benign conditions including cholangitis, due to other causes, e.g. choledocholithiasis. However, in such cases the increase is not significant and it is usually below 1000 u/ml. Values more than 10000 u/ml are limited to few case reports in articles. The case under study was a 66 year old man hospitalized because of epigastric and right upper quadrant pain, fever, jaundice, acholic stool, weight loss of about 6 kg, and hyperchromic urine. Physical examination revealed that the case was icteric and febrile with a mild RUQ tenderness on percussion. Laboratory tests showed marked elevation of bilirubin and CA19-9 (Total bilirubin: 36 mg/dl, Direct: 19.5 mg/dl CA19-9 :44777u/ml, Normal: 0-40 u/ml), but the enzymes of the liver and alkaline phosphatase only increased to two times the normal level. Sonography showed dilated common bile duct with four stones within it. Four weeks after stones extraction and renewal of bile current CA19-9 fell to 60 u/ml and returned to normal range (0-40) 2 months later and during this period the patient was totally asymptomatic. As a result, in patients with biliary obstruction, a diagnosis of malignancy cannot be made solely on the basis of increased concentration of CA19-9, even in case of high clinical suspicion and the interpretation of this increase must be done with more caution and after lab follow-up following removal of the obstruction.