Hepatopulmonary syndrome(HPS) is characterized by hypoxemia and intrapulmonary vasodilation and develops in patients with liver disease. It is important to diagnose HPS, as the syndrome is associated with high morbidity and mortality. Although Orthotic liver transplantation (OLT) has been shown to reverse HPS, little in known about the long term natural history of patients with HPS or the optimal timing for OLT. The aim of this study is to investigate the accuracy and utility of pulse oxymetry in the detection of hypoxemia (PaO2<65). Three hundred thirteen transplant candidates unrolled in this study. Arterial oxyhemoglobin saturation was obtained by pulse oxymetry and compared with simultaneous artenial blood gas (ABG) oxyhemoglobin values. (SaO2) biase difference). SPO2 overestimated in 82.11%, and 16.29% had a bias of 4% or greater. SPO2, SaO2, PaO2 <65 or A-aO2 gradient > 15 were associated with more significant bias (P=0.000). SPO2 and SaO2 were less than 94% in 7.99(N: 25) and 20.77% (n: 65) of the patients respectively.