Evaluate the Efficacy and Safety of One Course of Amevive in Taiwan Patients

• Must give written informed consent
• Must be >= 16 years of age
• Must have been diagnosed with chronic plaque psoriasis at least one year and require systemic or phototherapy
• Must have CD4+ lymphocyte count at or above the lower limit of normal
• Must have a BSA >= 10%

Exclusion Criteria:

• Current erythrodermic, generalized pustular, or guttate psoriasis
• Serious local infection or systemic infection within 3 months prior to the first dose of alefacept
• History of any clinical significant disease that would be contraindicated for this study as determined by the investigator
• Prior history of systemic malignancy, untreated localised skin canceer or a >10 squamous cell carcinoma
• Current enrollment in any other investigational drug study within 30 days prior to study drug administration
• Treatment with systemic immunosuppressant agents within the 4 weeks prior to study drug administration.