Intraoperative indocyanine green (ICG) lymphography was performed on a 62-year-old man, who was diagnosed to have chylothorax after an esophagectomy for esophageal cancer. After exploration of the thorax, a slowly increasing effusion was identified in the mediastinal space above the diaphragm, but the exact site of the lymph fistula could not be identified. By injecting 1.5 ml of ICG subcutaneously at the bilateral inguinal region, fluorescence images of the lymph flow in the thoracic cavity were obtained using a near-infrared camera system. The detected leakage point was sutured and the chyle ooze stopped. The postoperative course was uneventful. The patient was discharged on the 16th postoperative day. This is the first report using ICG fluorescence lymphography for the successful intraoperative detection of the exact site of a fistula causing chylothorax.