An 81-year-old man was admitted to our hospital with dyspnea on exertion and hypoxemia. Although the chest computed tomography (CT) scan showed mild bilateral subpleural reticular opacities in the lung posterior, pulmonary function testing was normal. The abdominal CT scan showed a fatty liver. Whole body blood flow scintigraphy with ^99mTc-MAA revealed an intrapulmonary right-to-left shunt in 14.5% of the entire body. Therefore, he was diagnosed with hepatopulmonary syndrome (HPS) and a fatty liver. He was started on oxygen therapy, diet, and total abstinence from alcohol. The hypoxia gradually improved and the oxygen therapy was discontinued 9 months thereafter. Weight loss was achieved and the fatty liver disease also improved, as shown on the abdominal CT scan. In a case with suspected HPS derived from a fatty liver, improvement in hypoxia may be accompanied by amelioration of the fatty liver disease.