A 53-year-old woman was admitted with right massive transudative pleural effusion and acute renal failure. The amount of pleural fluid reduced in response to treatment with hydration and diuretics; however, the effusion recurred one month later. We suspected the presence of a right pleuroperitoneal communication allowing pleural fluid to accumulate from an origin of ascites triggered by renal failure. Chest computed tomography following pleural drainage revealed a small nodule in the right upper lobe of the lung. A diagnosis of T1aN0M0 lung adenocarcinoma was made based on the results of various examinations, including bronchoscopy. Video-assisted thoracoscopic surgery was performed, and the presence of a small hole communicating between the pleural and peritoneal cavities was confirmed in the right diaphragm during the surgery.