We present a case of the successful use of bosentan for increased pulmonary vascular resistance (PVR) in a 10-year-old male who underwent late single ventricle surgical palliation for double-inlet left ventricle with pulmonary artery banding and a bidirectional Glenn shunt. The patient was treated with bosentan for 16 weeks, with decreases in mean pulmonary artery pressure from 23 to 16 mmHg on the right and from 31 to 21 mmHg on the left, and a decrease of the transpulmonary gradient by 7-8 mmHg. Cardiopulmonary exercise testing demonstrated an increase in peak oxygen consumption (VO2) by 8% and peak work rate by 10%. Bosentan is a relatively new oral therapy option for increased PVR in patients with single ventricle physiology and bidirectional Glenn shunts.