Chylothorax is a pathological condition associated with the accumulation of lymphatic fluid in the pleural cavity. This pathology occurs quite rarely, but it is a complex and often life threatening disease that results in deep respiratory, metabolic and immunological disorders. Occurs in any age group, including the neonatal period. Currently, there are few reports of congenital chylothorax, no practical recommendations for the clinical management of this category of patients, mortality is from 20 % to 60 %. At present, there is no single point of view regarding the pathogenesis of the occurrence of chylothorax. In the modern literature, the following etiopathogenetic factors are indicated: iatrogenic causes (cardiothoracic surgical interventions, puncture of the central veins from the system of vena cava superior, trauma during labor), increased pressure in the system of the upper vena cava (thrombosis, congenital malformations of the heart), diaphragmatic hernia, congenital defects of lymphatic system (hypoplasia of vessels or vascular walls), lymphangiomatosis, genetic defects (Down syndrome, Noonan, monosomy X, etc.), congenital cytomegalovirus infection, inflammatory process. Infants in whom chylothorax has been diagnosed with up to 35 weeks of gestation and initiated prenatal treatment have improved postnatal results. In the postnatal period, the initial steps of the treatment include drainage of the pleural cavity, adequate ventilation, parenteral nutrition, specific enteral nutrition (a formula with high protein content, reduced lipid content, and, instead, should contain mid chain triglycerides - MCT), correction of albumin content, electrolytes (typical hyperkaliemia, hyponatremia) and drug therapy (octreotide). The clinical case of a premature baby with congenital bilateral chylothorax is an example of successful conservative treatment.