Liquid biopsy is a rapidly evolving diagnostic technique used to analyse tissue-derived information found in the blood or other bodily fluids. It represents a new way to guide therapeutic decisions mainly in cancer, but its application in other fields of medicine is still growing. Here, we discuss how liquid biopsy has been used in autoimmune rheumatic diseases such as rheumatoid arthritis, systemic lupus erythematosus or primary Sjögren's syndrome. Additionally, in aspect of liquid biopsy, we analyse the molecular biomarkers utilised in the field of rheumatology including circulating cell-free DNA, microRNA and proteomic content.