BACKGROUND About 80% lung cancer is non-small cell lung cancer (NSCLC) and more than 70% are in advanced stage. The aim of this study is to evaluate the clinical efficacy and the side effects of erlotinib in the treatment of elderly patients with advanced non-small cell lung cancer. METHODS Twenty-nine patients with advanced non-small cell lung cancer were treated with erlotinib 150 mg/d, then the adverse reaction and clinical efficacy were recorded during 3 months. RESULTS Total 29 patients were evaluated for efficacy. The total rate of effect was 20.69%, including 1 case CR, 5 cases PR, 9 cases SD and 14 cases PD. We compared the effective rate of stage III with IV. There were no significant difference between the effective rate of stage III and IV (P=0.337). The main side effects were rash (37.93%), diarrhea (17.24%) and vomiting (6.9%) and most side effects were grade I and II. CONCLUSIONS Erlotinib for elderly patients with advanced non-small cell lung cancer have better effective and less toxic effects and the further clinical study should be warranted.