Nontraumatic chylothorax is an uncommon condition of thoracic or abdominal origin caused by multiple disorders, of which malignancy is by far the most frequent one. Because gross appearance of pleural fluid is frequently misleading, pleural fluid and serum lipid analysis is required for its diagnosis. In addition to the presence of chylomicrons, chylothoraces are usually characterized by all three of the following: (1) a triglyceride level of more than 110 mg/dL; (2) a ratio of pleural fluid to the serum triglyceride level of more than 1.0; and (3) a ratio of the pleural fluid to serum cholesterol level of less than 1.0. In patients with lymphoma-related chylothorax refractory to chemotherapy and radiation therapy, medical thoracoscopic talc pleurodesis has an acceptable complication rate and a 100% success rate in the prevention of recurrences. Pleuroperitoneal shunting is considered a safe and effective treatment in the management of persistent chylothorax in children in the absence of chylous ascites.