The patient was a 71-year-old man with pleural effusion secondary to adenocarcinoma of the lung. Systemic chemotherapy with gemcitabine (GEM) and vinorelbine (VNR) was administered. This treatment brought a decrease in pleural effusion. After three cycles of the regimen with GEM and VNR, the regimen was changed to weekly paclitaxel. However, the paclitaxel regimen was not effective. Therefore, we returned to the former regimen. However, the pleural effusion was refractory to that regimen, and increased. We then added 5-FU to the regimen. This addition again brought a decrease in the pleural effusion, suggesting that the additional administration of UFT is effective against refractory malignant pleural effusion after the treatment regimen with GEM and VNR.