Lung cancer is a leading cause of cancer deaths worldwide. Although the molecular pathways of lung cancer have been partly known, the high mortality rate is not markedly changed. MicroRNAs (miRNAs) are small noncoding RNAs that actively modulate cell physiological processes as apoptosis, cell-cycle control, cell proliferation, DNA repair, and metabolism. Several studies demonstrated that miRNAs are involved in the pathogenesis of lung diseases including lung cancer and they negatively regulate gene and protein expression by acting as oncogenes or tumor suppressors. In this review we summarize the current knowledge on the role of miRNAs and their target genes in lung tumorigenesis and evaluate their potential use as therapeutic agents in lung cancer. In particular, we describe methodological approaches such as inhibition of oncogenic miRNAs or replacement of tumor suppressor miRNAs, both in in vitro and in vivo assays. Furthermore we discuss new strategies to achieve in vivo tissue specific delivery, potential off-target effects, and safety of miRNAs systemic delivery.