We report an unusual case of severe hepatopulmonary syndrome with previously unrecognized cirrhosis, presenting with acute on chronic dyspnoea, extreme hypoxemia, secondary polycythemia as well as direct identification of arteriovenous communications on computed tomography angiography. Hepatopulmonary syndrome, defined as the combination of hepatopathy, arterial deoxygenation and pulmonary vascular dilatation, is increasingly recognized as a life-threatening complication in advanced liver disease and transplant candidacy. It is usually diagnosed in chronic liver disease patients following pre-transplant evaluation or mild dyspnea investigation. Diagnosis relies on the indirect evidence of pulmonary arteriovenous communications suggested by echocardiography with a bubble study. Clinicians need to be aware of this rare but potential acute presentation at the emergency room.