Two decades ago, the introduction of the TNF inhibitors revolutionised the treatment of rheumatoid arthritis and spondyloarthritis. In the years to follow, more targeted therapies where introduced for rheumatoid arthritis. However, there has been an unmet need of an oral agent, with comparable efficacy as the biologics. Further, few alternative biologics have been available for patients with spondyloarthritis. In this review thesis, the biologic agents used to date, the new therapeutic agents targeting the IL-23/IL-17 axis and the Janus kinase, and their molecular background will be discussed.