Lung cancer is one of the major cancers, and survival of lung cancer patients is dictated by the timely detection and diagnosis. Cell-free circulating microRNAs have been identified as potential biomarkers for early detection and diagnosis of lung cancer. The review considers the main techniques to extract microRNA from various biological fluids, approaches to the analysis of microRNA concentration and composition, and the potential of microRNAs as biomarkers for lung cancer. The identification of informative biomarkers is crucial for the development of effective diagnostic and therapeutic strategies for lung cancer.