Case one was a 76-year-old woman. She was diagnosed as having lung adenocarcinoma with multiple metastases (cT4N0M1, stage IV, mucinous BAC)in June, 2004. Starting in July, 2004, she received various modalities of chemotherapy( cisplatin+vinorelbine, gefitinib, pemetrexed, gemcitabine, docetaxel, paclitaxel). S-1 monotherapy given to her starting April, 2006 achieved a partial response(PR)as a seventh-line treatment. Case two was a 60-year-old woman. She was diagnosed as having lung adenocarcinoma with multiple metastases(cT4N3M1, stage IV)in October, 2004. That month, her chemotherapy began. After various treatments(cisplatin+vinorelbine, docetaxel, gefitinib), S-1 monotherapy was initiated in February, 2007 as the fourth-line treatment; as a result, PR was achieved. Even though chemotherapies were performed in succession, in the condition of good general status, salvage chemotherapy can be affected by the rotation of drugs. In such cases, S-1 monotherapy can be a reasonable choice from the standpoint of feasibility and effectiveness.