Lung cancer is the leading cause of death from malignancy worldwide. Its heterogeneity and tumour biology make treatment considerably more difficult. The introduction of target molecules heralded the beginning of the personalized medicine which tailors medical treatments to the molecular and genetic profile of a patient. Liquid biopsy is an innovative, non-invasive method which is used both for diagnostic purposes and for therapeutic monitoring. Liquid biopsy has the potential to help manage non-small cell lung cancer throughout all stages of this cancer: screening, detection of minimal residual disease to guide adjuvant treatment, early detection of relapse, systemic treatment initiation, monitoring of response to targeted or immune therapy, and the emergence of resistance to applied treatment. At present, the study of circulating tumour DNA is used in clinical practice, but circulating tumour cells, miRNAs, exosomes, and platelets formed in the tumour also show promising results.