Tumor necrosis factor-alpha is a major effector and regulatory cytokine, which seems to have an outstanding position in rheumatic and other inflammatory states. Because TNF-alpha has been detected in the inflamed gut and sacroiliac joints of patients with chronic inflammatory bowel diseases and spondyloarthritides, like ankylosing spondylitis, there was need for studies of the efficacy of the modern biologic anti-TNF agents infliximab and etanercept in these diseases. Infliximab is approved for the treatment of Crohn disease. In addition, there are now also positive data for infliximab in the treatment of ankylosing spondylitis and for etanercept and infliximab in the treatment of psoriatic arthritis.