We report 3 cases of long-term control achieved via S-1 monotherapy in elderly patients with advanced non-small-cell lung cancer. In case 1, a 75-year-old man clinically diagnosed with stage IIIA lung adenocarcinoma received S-1 as fourthline chemotherapy. PR was achieved, and PFS was 8 months. In case 2, a 78-year-old woman clinically diagnosed with stage IV lung squamous cell carcinoma received S-1 as third-line chemotherapy. A PR was achieved, and PFS was 14 months. In case 3, an 83-year-old man clinically diagnosed with stage IV lung squamous cell carcinoma received CBDCA plus PTX, followed by S-1 on alternate days. Although tumor size was not reduced, SD was maintained for 11 months.