Chylothorax is a rare clinical condition that can be attributed to a damaged thoracic duct. The condition is suggested by aspiration of milky white fluid from the pleural cavity and is commonly associated with either malignant diseases or trauma (e.g. cardiothoracic surgery). We present the case of a 15-year-old boy with chylothorax, whose effusion was due to constrictive pericarditis. The definitive treatment of chylothorax involves identification and management of the underlying pathology. We suggest that when dealing with cases of chylothorax, constrictive pericarditis should be considered among the causes.