Inclusion Criteria:

1. Are at least 18 years old.
2. Have plaque psoriasis with an sPGA score of at least moderate or severe at time of initiation of previous systemic treatment.
3. Are transitioning from methotrexate, cyclosporine, retinoids, PUVA or NBUVB and initiating treatment with Raptiva according to the decision of the investigator and in accordance with the indication and the recommendations of the Raptiva Investigator Brochure, i.e. to which they have failed to respond, have a contraindication to or are intolerant of other systemic therapies.
4. Agree to participate in the study, and to disclose any medical events to the investigator. The subject must be willing and able to comply with the protocol requirements for the duration of the study.
5. Have given written informed consent with the understanding that consent may be withdrawn at any time without prejudice to future medical care.
6. Women of childbearing potential must use appropriate contraception during treatment and up to the last study visit (safety follow-up visit). For men, it is also mandatory to practice contraception during participation in the trial, as there are no existing data on the effect of Raptiva on spermatogenesis.
7. Discontinuation of any investigational drug or treatment 3 months prior to study start or as per washout requirements from previous protocol.

No primary vaccinations (e.g., tetanus, booster, influenza vaccine) for at least 14 days prior to first dose of study drug.For the purposes of this trial, women of childbearing potential is defined as: "All female subjects after puberty unless they are post-menopausal for at least two years, are surgically sterile or are sexually inactive."

Exclusion Criteria:

1. Any contra-indication to Raptiva, according to the Investigator Brochure, or as follows:

   • Hypersensitivity to Raptiva or to any of the excipients.
   • Subjects with history of malignancies.
   • History of active tuberculosis (TB) or currently undergoing treatment for TB. PPD testing or chest X-ray is required for high-risk subjects (see Appendix E). Subjects with a positive PPD (not due to BCG vaccination) or chest X-ray will be excluded.
   • Subjects with specific forms of psoriasis like guttate, erythrodermic or pustular psoriasis as sole or predominant form of psoriasis.
   • Subjects with immunodeficiencies.
2. Simultaneous participation in another clinical trial.
3. Subjects experiencing a psoriasis exacerbation during screening period.
4. Subjects who have previously been on Raptiva treatment who withdrew due to lack of efficacy or an adverse event. If withdrawal was due to another non-drug reason (vaccination, or infection) then the subject can be included in this study.
5. History of hepatitis B, hepatitis C or human immunodeficiency virus (HIV).
6. History of thrombocytopenia, haemolytic anaemia or clinically significant anaemia.
7. Hepatic enzyme levels ³3 times the upper limit of normal or serum creatinine level ³2 times the upper limit of normal.
8. Pregnant or breast-feeding.
9. Any medical condition (prior or existing) that, in the judgment of the investigator or sponsor, could jeopardize the subject's safety following exposure to study drug.