The hepato-pulmonary syndrome (HPS) is a rare complication of liver cirrhosis, with poor outcome; the term includes liver disease, increased alveolo-arterial gradient and intrapulmonary vascular dilations, described by Fluckiger, Kennedy and Knudson. HPS impairs survival in cirrhotic patients and the posttransplant outcome is altered in correlation with severity of HPS. Combined determination of SaO2 in clino- and orthostatic position by a pulsoximeter is a simple test for HPS identification in patients with chronic liver disease or non-cirrhotic portal hypertension.