Pulmonary arterial hypertension (PAH) in patients with portal hypertension is also referred to as portopulmonary hypertension (PPHTN). Here, we report a case of PPHTN caused by alcoholic liver cirrhosis in a 43-year-old male who experienced repetitive syncope on exertion. The continuous monitoring of pulmonary artery pressure and radial artery pressure revealed that his PAH was aggravated with a drop in systemic arterial pressure during an exercise test. Bosentan, an endothelin A/B receptor antagonist, improved the patient's hemodynamic parameters and abolished his syncope without adverse effects. This is the first report that bosentan may be effective and safe for PPHTN associated with syncope.