Psoriasis is a chronic, recurrent skin disease that lasts a whole life. A quarter of adults are suffering from severe forms of psoriasis that requires the application of the systemic treatment. Despite the development of new groups of medicines, traditional therapy is still of great importance. Methotrexate, cyclosporine and acitretin are cost-effective and provide excellent disease control. Methotrexate and acitretin are good choice in terms of maintenance therapy, whereas cyclosporin would ideally be used as intermittent therapy. Fear of serious side effects of traditional drugs can be avoided by setting individualized plan for each patient and careful monitoring.