Inclusion Criteria:

• Patients of either sex at least 18 years of age
• A clinical diagnosis of plaque psoriasis defined as skin areas with erythema, induration and scaling, with a body surface area of no less than 10% and in total to be scoring at least 10 on the PASI scale
• The psoriasis disease have been stable for at least 6 months at randomization
• Signed and dated informed consent

• Sexually active females of childbearing potential must be either surgically sterile (hysterectomy or tubal ligation) or use a highly effective (failure rate < 1%) medically accepted contraceptive method during the trial as well as one month after trial is finished such as:

  • Systemic contraceptive (oral, implant, injection),
  • Intrauterine device (IUD) inserted for at least one month prior to study entrance
• Willingness and ability to comply with the trial procedures
• Patient is beside the psoriasis disease in good general health in the opinion of the Investigator, as determined by medical history, physical examination, vital signs and clinical laboratory parameters (hematology, biochemistry and urinalysis).

Exclusion Criteria:

• Female patients who are pregnant or breast-feeding or planning to become pregnant up to 7 months from treatment start as well as male patients plan-ning pregnancy with their partner up to 7 months from treatment start or practise unprotected sexual relationship up to 7 months from treatment start
• Known allergy to any of the constituents of the product being tested
• Pustular forms of psoriasis, erythrodermic or guttate psoriasis
• Known immunosuppressive diseases (e.g., AIDS/HIV)
• Presence of another serious or progressive disease which, according to the Investigator may interfere with treatment outcome
• Active skin disease such as atopic dermatitis, rosacea, lupus erythematosus, or other inflammatory or infectious skin disease which, according to the Investigator may interfere with treatment outcome
• Use of topical medical treatment or UVB treatment - Use of systemic anti-psoriatic treatment preceding the baseline visit Methotrexate, cyclosporine, steroids or PUVA treatment within x weeks; Biological treatment (efalizumab, adalimumab, infliximab, etanercept) within xx weeks; Acitretin within x months; Treatment with Fumaderm® or other DMF containing products during past xx weeks prior to baseline visit; Discontinuation of previous treatment with Fumaderm® or other DMF containing products due to lack of efficacy or side effects;
• Has within the past x weeks prior to baseline visit been treated with drugs influencing the course of the psoriasis such as antimalarial drugs, beta-blockers or lithium
• Has a relevant clinical history of stomach or intestinal problems (eg gastritis or peptic ulcer within the last 10 years )
• Has liver enzyme measures (AST, ALT, Gamma-GT) higher than 2x UNL)
• Has an estimated Creatinine Clearance: < xx ml/min
• Has leucopenia (leukocyte count < x/mm3) or eosinophilia (count >x/µl) or lymphopenia (count < x/nl).
• Has protein in the urine test at screening or baseline visit
• Participation in another clinical trial during the last month preceding the baseline visit or participation in a trial with treatment of biologicals within x months prior to baseline visit
• Patients who are involved in the organisation of the clinical investigation or are in any way dependant on the investigator or sponsor