Treatment with third-generation chemotherapy agents improves survival and quality of life of patients with non-small-cell lung cancer (NSCLC). Despite these favorable outcomes, most patients receiving front-line therapy experience disease progression. The availability of many new novel agents with activity in NSCLC has prompted investigators to explore second-line chemotherapy options. For many years, docetaxel was the only approved agent for the second-line treatment of NSCLC. More recently, the multi-targeted antifolate pemetrexed has demonstrated activity in patients previously treated with chemotherapy with locally advanced or metastatic NSCLC. The findings of a phase III trial comparing pemetrexed to docetaxel led to the regulatory approval of pemetrexed as monotherapy for the second-line treatment of NSCLC. Several other novel therapies, including molecular targeting agents such as erlotinib, are under development in clinical trials in patients with NSCLC. One of these trials has subsequently led to the approval of erlotinib as second- or third-line therapy in advanced NSCLC.