Chylothorax is the result of pleural effusion caused by accumulation of chyle or lymphatic fluid in the pleural cavity. In the first months of life it occurs after correction surgery of congenital heart anomalies like heart defects, esophageal atresia or diaphragmatic hernia. Some are congenital in origin associated or not with other defects (mostly chromosomic derangements). Conservative treatments are intended to minimize or avoid lymphatic flux in order to attain the defect closure. Seventy percent of patients ameliorate by the use of especial long-chain free and middle-chain triglyceride (MCT) enriched formulas. Fat-free human milk obtained by centrifugation, enriched or not with middle chain triglycerides, has been successfully used as a treatment. Fully fasting and total parenteral nutrition is sometimes needed. Octreotide (octapeptide somatostatin analogue) may be another option. The mean for normal feeding initiation is 9 days (3 to 59 days), thus it is important to know if milk production is desirable to maintain by means of frequent pump extraction and freezing. The best result among different conservative treatments is not clearly defined. Corrective surgery is a difficult decision when conservative treatments have failed.