Psoriatic arthritis (PsA) is a form of inflammatory arthritis that occurs in patients with psoriasis and is distinct from rheumatoid arthritis (RA). Methotrexate (MTX) is one of the most commonly used drugs for the treatment of PsA, yet there is scant controlled trial data to document its efficacy. Controlled trials have not demonstrated significant separation from placebo, but the studies have significant limitations which inhibit our ability to draw firm conclusions about the efficacy of MTX. A number of observational studies have described benefit for joint and skin disease. As yet unstudied, are the effects on enthesitis, dactylitis, and spondylitis of PsA. Psoriasis studies have shown modest benefit for psoriatic skin lesions. It is not yet known if MTX contributes an additive or synergistic benefit when used in combination with TNF inhibitors in PsA. The potential value of low dose MTX to suppress antibody formation against biologic therapies should be considered in a patient fail- ing benefit from such therapy. Although adverse effects are similar to those seen in RA treatment with MTX, awareness of the tendency for PsA and psoriasis patients to be obese and have non-alcoholic steatohepatosis, which may amplify transaminitis potential, should be borne in mind.