We present a patient with acute-onset dyspnea and unexplained severe hypoxemia. No signs of severe cardiopulmonary disease, pulmonary arterial hypertension, or pulmonary embolism were present. The patient was diagnosed with hepatopulmonary syndrome, since liver disease of alcoholic origin was present, markedly increased alveolar-arterial oxygen difference existed, and intrapulmonary vascular dilations were demonstrated. The condition of the patient did not improve and he was referred for liver transplantation, which is the only treatment option with documented efficacy. The case highlights the importance of thinking outside the thorax when evaluating patients with dyspnea.