A Study to Evaluate Raptiva in Adults With Plaque Psoriasis Previously Enrolled in Study ACD2390g

Inclusion Criteria: * Signed informed consent * Previous participation in Study ACD2390g * For women of childbearing potential, continued use of an acceptable method of contraception for the duration of their participation in the study * Willingness to continue to hold sun exposure reasonably constant and to avoid use of tanning booths or other UV light sources throughout the study Exclusion Criteria: * Any medical condition that, in the judgment of the investigator, would jeopardize the subject's safety following exposure to efalizumab * Systemic therapy for psoriasis (ET Day 0 through FU Day 84 or upon relapse or unusual presentation of psoriasis in the FU period, whichever occurs first) * Systemic immunosuppressive drugs for other indications (ET Day 0 through FU Day 84) * Topical therapies for psoriasis (ET Day 0 through ET Day 84) * Live virus or bacteria vaccines (ET Day 0 through FU Day 84) * Other vaccines or allergy desensitization (it is recommended that these be scheduled after FU Day 84) * Other experimental drugs or treatments (ET Day 0 through FU Day 84) * Beta-Blockers, ACE inhibitors, interferons, quinidine, antimalarial drugs, or lithium (if clinically indicated, such medications are allowed but the dosage should be held constant between ET Day 0 and TT Day 84)