The proinflammatory cytokine TNF alpha is in the pathogenesis of PsA as important as in RA. TNF-alpha is increased in the psoriatic skin lesion and in the synovium of the inflamed joint. The TNF alpha blockage has been tested in double blind trials with etanercept and infliximab. All studies proved a significant and durable response in the reduction of synovitis in a comparable extend in both drugs. Etanercept showed after 12 weeks an ACR20 response in 59% of the patients versus 15% in the placebo arm. Infliximab had after 14 weeks a 69% ACR20 response versus 8% placebo response. The psoriatic skin lesion improved with both drugs. The PASI was reduced by 47% with etanercept and by 81% with infliximab. The safety-profile was similar to the RA-trials. For etanercept the one year data have shown a reduction in x-ray progression. Etanercept has been approved in the USA and in Europe.