Lung cancer is a heterogeneous disease with currently still unknown mechanisms of development. Besides genetic and epigenetic mechanisms, microRNAs (miRNAs) have recently been discovered as one of the crucial players in lung carcinogenesis through posttranscriptional regulation of tumor suppressor and oncogenes. A substantial number of deregulated miRNAs have been revealed in lung cancer, and the biological significance of those miRNAs has been confirmed in multiple functional experiments. A growing number of studies suggest involvement of miRNAs in various steps of lung carcinogenesis. Great biological stability of miRNAs opens novel fields in biomarker research with potential clinical implementation in screening, diagnosis and prediction of prognosis. In this review, we provide the basic knowledge of miRNA biogenesis and discuss extensively the role of miRNAs in lung carcinogenesis, including potential translational clinical implementations.