Bile leakage into the thoracic cavity is a rare complication of invasive cancer. A 12-year-old boy was diagnosed with undifferentiated sarcoma of the right lobe of the liver invading the diaphragm. An extended right hepatectomy and total resection of the mass was performed, leaving a patchy tumoral invasion at the anterior diaphragmatic surface. Surgery was followed with a combined chemotherapy regimen. In the sixth postoperative month, he was readmitted with bilious expectoration. Tc-99m mebrofenin hepatobiliary scintigraphy revealed radiotracer accumulation in the right hemithorax. Bile leakage into the right thoracic cavity was diagnosed based on the hepatobiliary scintigraphic findings. For this patient; hepatobiliary scintigraphy, which is routinely used to visualize the liver and biliary tree, provided a noninvasive mean for the precise diagnosis of a bronchobiliary fistula. The fistula was then confirmed and corrected with surgery. The patient recovered uneventfully.