Recent work in experimental models of HPS has revealed that both nitric oxide synthase-derived nitric oxide and heme oxygenase-derived carbon monoxide cause intrapulmonary vasodilatation. These alterations appear to be driven in part by TNF-α modulation of pulmonary blood flow and intravascular monocyte accumulation. Pentoxifylline is a nonspecific phosphodiesterase inhibitor with inhibitory effects on TNF-α and has recently been shown to be beneficial in patients with severe alcoholic hepatitis where TNF-α overproduction contributes to liver injury. In experimental HPS, pentoxifylline administration also decreases the severity of oxygenation abnormalities. However, pentoxifylline therapy has been associated with dose limiting side effects in patients with liver disease and the tolerability of pentoxifylline in cirrhotic patients with advanced HPS is unknown. Therefore, this open label single arm clinical trial was designed to evaluate the efficacy and tolerability of 8 weeks of pentoxifylline in cirrhotic patients with advanced HPS being considered for OLT.