The development of pulmonary arterial hypertension in the setting of portal hypertension is known as portopulmonary hypertension. Portal hypertension is thought to predispose patients to disturbances in the homeostatic regulation of numerous neurohumoral and vasoactive mediators that induce the development of pulmonary arterial hypertension. Portopulmonary hypertension is pathologically indistinguishable from idiopathic pulmonary arterial hypertension and is characterized by the development of vasoconstriction, vascular remodeling, and thrombosis within the pulmonary vasculature. Although described in patients with both cirrhotic and noncirrhotic portal hypertension, portopulmonary hypertension is most prevalent among patients with end-stage liver disease, and its severity seems to be independent of the etiology or severity of liver disease. All liver transplant candidates must be screened for the presence of portopulmonary hypertension because of the high perioperative mortality risk of liver transplantation associated with this condition. Primary screening for portopulmonary hypertension consists of doppler-estimated pulmonary artery systolic pressure measurement during echocardiography. However, the diagnosis of portopulmonary hypertension is based on unique hemodynamic criteria as determined by right heart catheterization. Untreated portopulmonary hypertension portends a poor prognosis, and the efficacy of current treatment modalities is limited. At present, the primary goals of therapy are to provide symptomatic relief, prolong survival, and improve pulmonary hemodynamics to facilitate safe and successful liver transplantation.