Lung cancer is the most commonly diagnosed cancer as well as the leading cause of cancer-related deaths worldwide. To date, surgery is the first choice treatment, but most clinically diagnosed cases are inoperable. While chemotherapy and/or radiotherapy are the next considered options for such cases, these treatment modali-ties have adverse effects and are sometimes lethal to patients. Thus, new effective strategies with minimal side effects are urgently needed. Cancer immunotherapy provides either active or passive immunity to target tumors. Multiple immunotherapy agents have been proposed and tested for potential therapeutic benefit against lung cancer, and some pose fewer side effects as compared to conventional chemotherapy and radiotherapy. In this article, we discuss studies focusing on interactions between lung cancer and the immune system, and we place an emphasis on outcome evidence in order to create a knowledge base well-grounded in clinical reality. Overall, this review highlights the need for new lung cancer treatment options, with much ground to be paved for future advances in the field. We believe that immunotherapy agents alone or with other forms of treatment can be recog-nized as next modality of lung cancer treatment.