Mr M., 55-year-old, with metastatic adenocarcinoma of lung (stage IV) was admitted to the hospital after an earlier visit to oncology, where he presented with abdominal pain and distention suspected of having ascites for the first time. After performing abdominal CT and gastric passage film, it was hypothesized that clinical manifestation was related to gastric malrotation. The latter was forced by the huge left pleural effusion. Draining the pleural effusion may be complicated by a trapped lung, an adverse effect where the lung does not expand post drainage. After considering the palliative therapeutic options the effusion was drained, the stomach recoiled to its anatomical position, gastric malrotation was relieved, and the patient resumed oral nutrition. Though gastric malrotation due to a huge, malignant left pleural effusion is rare, it should be considered as more patients are being treated for lung cancer.