In this study, among the patients with non-small cell lung cancer, those with metastasis or recurrence and previous treatment with chemotherapy will receive gefitinib or docetaxel, and we will compare the effectiveness and safety of gefitinib with docetaxel.

Inclusion Criteria:

• You are "histologically" or "cytologically" confirmed to have recurrent or metastatic NSCLC
• You have been treated with chemotherapy including platinums for NSCLC.

Exclusion Criteria:

• You have received treatment for non-small lung cancer within 4 weeks before your participation in this study (except for specific therapies)
• You have or had any disease of acute lung injury, idiopathic pulmonary fibrosis, pulmonary pneumonia, or pneumoconiosis evident on the X-ray
• You have or had any disease of radiation pneumonia or drug-induced pneumonia, which requires treatment with corticosteroids