Abstract: Molecular targeted therapy is a new field, which appeared in recent years, with devel-opment of basic science and molecular biology of tumor. The agents act specific target's points such asreceptor, kinase, signal transduction system which related to the tumor growth, thus inhibting the pro-liferation, metastasis, vascularization, and promoting apoptosis of tumor. Iressa (gefitinib) is a smallmolecular agent through inhibiting epidermal growth factor receptor-tyrosine kinase for the treatment ofNSCLC. Since this was first targeted drug of its kind approved for the treatment of NSCLC, the articlefocuses on discussing clinical trial results and predictable factor of the agent for the treatment ofNSCLC.