Chylothorax is an infrequent complication of cardiac surgery in children. Most patients respond to a low-fat diet or to parenteral nutrition, but pleuroperitoneal drainage or thoracic duct ligature is sometimes required. We present the case of a 3-year-old girl with Down syndrome and complex atrioventricular canal defect who presented chylothorax 22 days after the Glenn procedure with bidirectional pulmonary-cava fistula. Low-fat diet and parenteral nutrition produced no improvement and the patient was treated with octreotide 1-2 mcg/kg/min in intravenous continuous perfusion, which produced remission of chylothorax. Subsequently, 20 mcg/kg/day of octreotide was subcutaneously administered in three doses, allowing progressive dietary normalization, without recurrence of chylothorax or adverse effects. In conclusion, octreotide is well tolerated and produces few adverse effects. It could be used as a therapeutic alternative in chylothorax refractory to conservative treatment.