miRNAs play an important role in the regulation of a wide assortment of cellular processes by sequestering target mRNAs and inhibiting translation of the proteins that they encode. Multiple miRNAs can regulate single mRNA molecules and, alternatively, a single miRNA can act on a number of mRNA targets. Dysfunctional miRNAs are commonly found in a variety of solid cancers and are attractive candidates for next-generation therapeutics. This article highlights miRNA signatures proposed for lung cancer classification and diagnosis, chemo- and radio-therapy resistance, metastasis and prediction of treatment outcome and survival.