The better understanding of immunology and antitumor immune responses have prompted the development of novel immunotherapy agents like PD-1 checkpoint inhibitors (anti-PD-1 and anti- PDL-1 antibodies) that improve the capacity of the immune system to acknowledge and delete tumors, including lung cancer. Currently, two anti-PD-1 (nivolumab and pembrolizumab) and one anti- PD-L1 (MPDL-3280A) agents are in advanced stages of development in advanced or metastatic non-small cell lung cancer (NSCLC). Among these, nivolumab demonstrated a survival benefit versus docetaxel in refractory squamous NSCLC, reporting 41% reduction in risk of death (median overall survival: 9.2 versus 6.0 months; objective response rate: 20% versus 9%), and better safety profile than standard-of-care chemotherapy (grade 3-4 adverse events: 7% versus 55%). However, the enhancement of immune response to cancer targeting specific immune regulatory checkpoints is associated with a toxicity profile different from that related to traditional chemotherapeutic agents and molecularly targeted therapies. The success of immunotherapy is related to ongoing evaluation/identification and treatment of these immunerelated side effects. Herein, first clinical results of PD-1 agents in lung cancer are reviewed, focusing on toxicity profile and its management.