Portopulmonary hypertension (PoPH) is a form of pulmonary arterial hypertension (PAH). PoPH occurs in approximately 15% of patients with PAH, and is reportedly found in 2-6% of patients with portal hypertension and 1-2% of patients with liver cirrhosis according to studies from Europe and America. However, the real-world data on PoPH in Japan are largely unknown, with many questions on the condition’s etiology and prevalence.