The investigators propose a French multicentre, randomized, double-blind, placebo-controlled trial to evaluate the efficacy of adalimumab in JIA-associated uveitis in patients over the age of 4 years. These patients must have active uveitis (Laser flare-cell meter score of at least 30 photons/ms) despite topical steroid therapy, with intolerance or failure to at least 3 months of MTX therapy. The dose of adalimumab will be 40 mg eow for children age 13 and over and for children younger than 13 adalimumab 24 mg per m2 BSA (up to a maximum total body dose of 40 mg). The activity of uveitis will be evaluated by laser flare photometry, a recently validated technique for follow-up of the efficacy of treatments of anterior uveitis. Seven hospital ophthalmology departments in France are equipped with laser flare photometry and have a sufficient experience to participate in this trial (Paris-Pitie-Salpetriere, Paris-Cochin, Nantes, Lille, Grenoble, Bordeaux and Lyon). Several teams of paediatric rheumatologists and hospital rheumatologists working with these ophthalmology departments will also be able to include patients. The primary endpoint is an at least 30% reduction of ocular inflammation after 2 months of treatment, quantified by laser flare photometry, considering the more severely affected eye in the case of bilateral uveitis. Based on the hypothesis of a response rate of at least 50% with adalimumab versus a maximum of 10% with placebo, comparison of two groups of 19 patients would be sufficient to conclude on a significant difference for a two-sided alpha risk of p=0.05 and a power of 80%. The investigators therefore plan to include 40 patients with randomization to two equal groups, one receiving 4 subcutaneous injections of adalimumab and the other receiving 4 injections of placebo on D0, D14, D28, and D42 with assessment of the primary endpoint at M2. The planned duration of inclusion is 2 years with a total duration of the trial of 3 years. From visit M2 onwards, all patients will be treated by adalimumab injections every 2 weeks and will be followed for 1 year of treatment. Clinical, laboratory and ophthalmological evaluation including laser flare photometry and conventional slit lamp examination will be performed at each visit (pre-inclusion, D0, D14, M1, M2, M3, M4, M5, M6, M9 and M12). Deterioration of ocular inflammation during the first 2 months will justify decoding for the patient concerned who will be considered to be a treatment failure.