Safety and Efficacy of Adalimumab to Methotrexate and Placebo in Subjects With Moderate to Severe Chronic Plaque Psoriasis

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.