Patients with advanced non-small cell lung cancer (NSCLC) who fail to respond to cytotoxic chemotherapy or who cannot tolerate chemotherapy have limited treatment options. In addition, patients with advanced NSCLC often experience disease-related symptoms that impact their quality of life. Treatment goals in this setting include palliation of symptoms and improvement in quality of life, in addition to tumor response or disease stabilization and increased survival. ZD1839 (Iressa, gefitinib) is an orally active, small-molecule, epidermal growth factor receptor-tyrosine kinase inhibitor that has shown single-agent efficacy for previously treated advanced NSCLC. In phase I clinical trials, ZD1839 provided relief from symptoms often associated with lung cancer, including fatigue, shortness of breath, and chest pain. The IRESSA Dose Evaluation in Advanced Lung Cancer (IDEAL)-1 and IDEAL-2 clinical trials evaluated ZD1839 treatment at 250 mg/day and 500 mg/day in patients with advanced NSCLC for objective tumor response and safety, as well as for improvements in NSCLC-related symptoms and health-related quality of life. The majority of patients enrolled in these studies had received multiple prior treatments. Rapid, sustained symptom improvement was documented for many patients receiving ZD1839 at 250 mg/day or 500 mg/day in both IDEAL trials and was positively associated with clinical benefits, such as tumor response and increased survival.