The major methods of microRNA extraction from different biological fluids (particularly, serum and plasma), approaches to the analysis of microRNA concentration and composition, normalization methods used in data analysis are outlined in the review. The advantages and disadvantages of the described methodological approaches are being highlighted. Special attention is given to microRNAs, circulating in blood, which could be used as the markers for minimally invasive lung cancer diagnostics, prediction of antitumor treatment efficiency and disease prognosis. Prospects and limitations arising from the evaluation of clinical significance of microRNAs as the potential tumor markers, and emerging as roles of various microRNAs in the pathogenesis of lung cancer become known, are discussed.