Biological therapies have become the centrepiece of the treatment of inflammatory bowel disease. They are not only able to induce and maintain clinical remission, but can also lead to endoscopic healing, the latter being associated with an improved long-term outcome, lower hospitalization and surgery rates, and an improved quality of life. The number of biological therapies is only expanding, currently including anti-TNF agents (adalimumab, certolizumab pegol, golimumab, infliximab), anti-integrins (vedolizumab), and anti-interleukins (mirikizumab, risankizumab, ustekinumab). All biological therapies have their own characteristics regarding mode of administration, onset of action, effectiveness, and potential adverse events. The selection of a specific molecule is therefore dependent on several factors and ultimately the result of a shared decision-making process. This chapter gives an overview of all currently available biological therapies.