This book concludes the results of the 2nd symposium on functional or regulatory autoantibodies targeting G-protein-coupled receptors (GPCRs) in Lubeck in 2018. GPCRs are involved in a variety of physiological and pathophysiological processes. So far, much effort has been made on anti-GPCR drug discovery with a focus on the development of small molecules for the treatment of cancer, infection, metabolic disorders or inflammatory diseases. Recently, functional autoantibodies against GPCRs were identified in healthy donors and were found to be dysregulated in various diseases. They are associated with pathogenesis, uncovering a potential new field of therapeutic intervention. Thus, the aim of the symposium in 2018 was to combine the current knowledge about the role of anti-GPCR ab in different pathologies, their mode of action and state-of-the-art research techniques to identify common fundamental pathways that can be transferred to other disease entities with similar manifestations.