An infant with chylothorax and polysplenia is described. Her chylothorax was refractory and related to right-sided heart failure derived from pulmonary stenosis, cor triatriatum, and sick sinus syndrome. In addition to Brock operation and cardiac pacing, thoracic duct ligation was performed, but it resulted in an only transient amelioration of the chylothorax. Eventually, the chylothorax resolved when total cardiac repair was performed for cor triatriatum. We propose that, in a patient with chylothorax and right-sided heart failure caused by compound cardiac malformations, as in this patient early surgical treatment for the underlying disease of right-sided heart failure should be considered.