Inclusion Criteria:

• Psoriasis involving at least 10% of the scalp and amenable to topical treatment with a maximum of 40g of gel per week.
• A score for the investigator's assessment of clinical signs of scalp psoriasis of at least 2 (moderate severity) in one of the clinical signs (redness, thickness and scaliness), and at least 1 (slight severity) in each of the other two clinical signs.
• An investigator's global assessment of moderate, severe or very severe scalp psoriasis.
• Psoriasis vulgaris of the trunk and/or limbs amenable to topical treatment with a maxi-mum of 60g of ointment per week.
• An investigator's global assessment of moderate, severe or very severe psoriasis of trunk/limbs.
• Attending a hospital out-patient clinic or the private practice of a dermatologist for treatment of psoriasis.
• Patients who self-report: - their ethnicity as Hispanic or Latino, and who are of any race, - their ethnicity as not Hispanic or Latino, and their race as Black or African American.
• Following receipt of verbal and written information about the trial, the patient must provide signed and dated informed consent before any trial-related activity is carried out.
• Females of child-bearing potential must have a negative result for a urine pregnancy test before randomisation and must agree to use an adequate method of contraception during the study.
• Patients fulfilling US requirements/law for participation in this study.

Exclusion Criteria:

• PUVA or Grenz ray therapy within 4 weeks prior to randomisation.
• UVB therapy within 2 weeks prior to randomisation.
• Systemic treatment with biological therapies (marketed or otherwise) with a possible effect on psoriasis (e.g., alefacept, efalizumab, etanercept, infliximab) within 3 months prior to randomisation.
• Systemic treatment other than biologicals with a possible effect on psoriasis (e.g., corticosteroids, vitamin D analogues, retinoids, hydroxycarbamide, azathioprine, meth-otrexate, cyclosporine, other immunosuppressants) within 4 weeks prior to randomisation.
• Any topical treatment of the scalp (except for medicated shampoos and emollients) within 2 weeks prior to randomisation (medicated shampoos/emollients are not allowed during the double-blind phase). Shampoos containing corticosteroids, e.g. Clobex®, are not allowed within 2 weeks prior to randomisation.
• Planned use of topical treatment for psoriasis of the trunk or limbs, besides study medication, during the study with the exceptions of: • emollient • medications used to treat psoriasis of the skin folds and/or genitals (any medication may be used for this purpose apart from Class 1-5 corticosteroids.
• Topical treatment of the face with Class 1-5 corticosteroids within 2 weeks prior to randomisation.
• Planned initiation of, or changes to, concomitant medication that could affect psoriasis (e.g., beta blockers, anti-malaria drugs, lithium) during the double-blind phase of the study.
• Treatment with any non-marketed drug substance (i.e., an agent which has not yet been made available for clinical use following registration) within 4 weeks prior to randomisation.
• Planned use of chemical treatments of the hair (eg relaxers, 'perms', or colourings) during the double-blind phase of the study.
• Current diagnosis of erythrodermic, exfoliative or pustular psoriasis.
• Patients with any of the following conditions also present on psoriatic areas of the scalp or trunk/limbs: viral (e.g. herpes or varicella) lesions of the skin, fungal or bacterial skin infections, parasitic infections, skin manifestations in relation to tuberculosis or syphilis, rosacea, acne rosacea, acne vulgaris, atrophic skin, striae atrophicae, fragility of skin veins, ichthyosis, ulcers or wounds.
• Other inflammatory skin diseases that may confound the evaluation of psoriasis of the scalp or trunk/limbs.