Chylothorax is a rare complication following coronary artery bypass graft surgery. In the following case, we report a chylothorax complicating left internal mammary artery harvesting due to injury of the left anterior mediastinal lymph node chain (LAMLNC) at the level of the proximal pedicle of the mammary artery. Re-expansion pulmonary edema occurred during re-operation for chylothorax following suturing of this lymph node chain. This observation demonstrates the role of the LAMLNC in both complications when injured or interrupted.