<qa>  What is the treatment of choice for?Psoriasis is an immuno-mediated skin disorder, which affects about 2-3 of the population worldwide. For moderate-severe forms of psoriasis systemic immunosuppression is the treatment of choice. This clinical trial was initiated to compare the safety and effectiveness of mycophenolate mofetil and cyclosporine A for the treatment of psoriasis. Patients are randomized to receive either 2.5 mgkg BW cyclosporine A or 1 g bid mycophenolate mofetil. If after six weeks no decrease in the PASI score occures cyclosporine A doses are increased to 5 mgkg BW for additional six weeks. In the other arm mycophenolate mofetil is increased to 1 g tid for additional six weeks. 