Tumor Necrosis Factor alpha (TNF) as proinflammatory cytokine plays in the pathogenesis of many diseases an important role. In psoriasis and in psoriatic arthritis TNF is up-regulated in the skin lesion and in the synovitis. Recent trials showed that the blockade of TNF with the chimeric antibody infliximab is able to improve both, the skin lesions and the synovitis of the joints. In psoriasis in 82% of patients treated with infliximab achieved an over 75% response in the PASI index. In Psoriatic arthritis the skin improvement was correlating with the reduction of synovitis and in a small MRI controlled study all patients achieved an ACR 20 response within 10 weeks. Patients with psoriatic arthritis, who have been included in spondylarthopathy trials showed similar improvement rates. In all trials unexpected safety problems have not been reported, but the trials have been small in population and short in duration. Infliximab was used between 5 and 10 mg/kg at week 0, 2, 6 and every 8 week. It some trials the retreatment periods varied. In contrast to the treatment of rheumatoid arthritis with infliximab methotrexate was not always used as comedication. In some cases infliximab has been used in combination with other DMARDs but no trial did evaluate the combination treatment vs. the monotherapy.