Pemetrexed is among the promising discoveries of the 21st century that changed treatment paradigm for a sub-population of lung cancer patients.Pemetrexed is a multitargeted antifolate that inhibits atleast three folate dependant enzymes involved in DNA synthesis. It is the first choice chemotherapeutic drug for advanced or metastatic non-small cell lung cancer (NSCLC) patients with nonsquamous histology.