patients with EGFR-mutated advanced NSCLC, the first-line treatment with gefitinib had achieved a significant prolongation of progression-free survival compared with standard platinum doublet chemotherapy in a few phase III trials, and became a new standard of care. Gefitinib is highly effective for patients with advanced NSCLC with EGFR mutation even if their performance status is poor, although one should always pay careful attention to fatal interstitial lung disease.