Systemic chemotherapy has remained the traditional treatment for metastatic non-small-cell lung carcinoma (NSCLC), enhancing survival rate at 1 year to 29%. The median survival had plateaued at around 10 months until early 2008, and in an attempt to enhance survival in advanced disease, maintenance chemotherapy trials were initiated which had recently demonstrated prolongation of survival by an additional 2–3 months in patients who had performance status (PS) 0–1 and well-preserved organ functions. Suitable patients with any degree of clinical benefit are treated with 4–6 cycles, and then one of the active agents is continued until best response, or toxicity (continued maintenance), or changed to a cross non-resistant single agent (switch maintenance). The article briefly reviews the evolution of systemic therapy and describes key randomised trials of maintenance therapy instituting chemotherapy and targeted agents in an attempt to improve outcomes in advanced metastatic NSCLC, based on certain clinical features, histology, and genetics