BACKGROUND/AIMS: The diagnosis of clonorchiasis is based on demonstrating eggs in stool or bile. It is believed that bile examination is the most precise method for detecting eggs. We evaluated diagnostic usefulness of intradermal test (IDT) by comparing it with the result of bile examination. METHODS: For 88 patients with pancreatobiliary diseases, we examined Clonorchis sinensis eggs in bile and performed IDT for clonorchiasis. The bile was obtained from endoscopic nasobiliary or percutaneous transhepatic biliary drainage tubes. RESULTS: We calculated ROC curve to decide the cut-off value of IDT in determining diagnostic accuracy on the basis of bile examination. We chose a value of 40 mm2, which significantly improved the sensitivity, without reducing the specificity. With a cut-off value of 40 mm2, the sensitivity, specificity, positive and negative predictive values of IDT were 81.5%, 67.2%, 52.4%, and 89.1%, respectively. The value of IDT was not affected by age and showed no difference between benign and malignant diseases. However, in egg-positive patients, the mean value was lower in malignant diseases than in benign diseases. CONCLUSIONS: In patients with pancreatobiliary diseases, IDT with a cut-off value of 40 mm2 seems to be a valuable supplementary diagnostic test for clonorchiasis in view of its high sensitivity.