The authors present the case of a 72-year-old woman who underwent coronary bypass grafting. Left sided chylothorax due to accidental dissection of a thoracic duct branch developed 2 months after sternotomy. As conservative therapy has failed, surgical pleurodesis was performed successfully. Chylothorax is a rare and underestimated complication of coronary bypass grafting. The worldwide increasing number of coronary artery bypass grafting surgeries makes it important to pay attention to this condition. Thus diagnosis of the chyle is relatively easy by its high chylomicron and triglyceride content, but identification of the etiology and its treatment is sometimes challenging for the physician. The treatment of chylothorax is usually conservative. The main goal is to keep the volume of the chyle under control. The number of surgical interventions because of chylothorax is increasing due to an increase of iatrogenic etiology.