• Proportion of subjects achieving clinical response at Week 16 relative to the Baseline (Week 0) PASI score. [ Time Frame: Week 16 ] [ Designated as safety issue: No ]
• Safety parameters [ Time Frame: Every Study Visit ] [ Designated as safety issue: Yes ]

• Physician Global Assessment [ Time Frame: Baseline - Week 16 ] [ Designated as safety issue: No ]
• PASI 50/90/100 [ Time Frame: Baseline - Week 16 ] [ Designated as safety issue: No ]
• DLQI [ Time Frame: Baseline - Week 16 ] [ Designated as safety issue: No ]

Placebo-Controlled Study Comparing the Safety and Efficacy of Adalimumab to Methotrexate and Placebo in Subjects with Moderate to Severe Chronic Plaque Psoriasis

• Drug: adalimumab
• Drug: MTX
• Drug: placebo adalimumab, placebo MTX

Inclusion Criteria:

• Subject was age 18 or older and in good health (Investigator discretion) with a recent stable medical history who has had a diagnosis of psoriasis for at least 12 months and stable moderate to severe chronic plaque psoriasis
• Subject is a candidate for systemic therapy or phototherapy and has active psoriasis despite treatment with topical agents.
• Subject was able and willing to self-administer sc injections or had available qualified person(s) to administer sc injections.
• Male subjects must hve been vasectomized or practicing birth control.

Exclusion Criteria:

• Previous systemic anti-TNF therapy.
• Prior use of MTX.
• Known hypersensitivity to the constituents of adalimumab.
• Systemic therapy for psoriasis for at least 4 weeks prior to Baseline; except for biologic therapies, which must be discontinued at least 12 weeks prior to enrollment.
• Topical psoriasis therapy for at least 2 weeks prior to Baseline, except for non-corticosteroid shampoos, bland (no alpha or beta hydroxy) emollients and low potency topical corticosteroids on the palms, soles, face, inframammary area, and groin only.
• Use of tanning beds, excessive sun exposure, or phototherapy (UVB, UVA), for at least 2 weeks prior to Baseline.
• Use of PUVA for at least 4 weeks prior to Baseline.
• Use of oral or injectable corticosteroids during the study.
• Subject considered by the investigator, for any reason, to be an unsuitable candidate for the study.
• Female subject who is pregnant or breast feeding or considering becoming pregnant.