Purpose: Aim of the present study was to validate a statistical model to predict a severe course of anterior uveitis (AU) in patients with juvenile idiopathic arthritis (JIA). Methods: Consecutive patients with newly diagnosed uveitis have been followed for at least 1 year with a standardized protocol. For each patient, demographic, clinical and laboratory characteristics, including time interval between arthritis and uveitis onset, alpha(2)-globulins level at arthritis onset, number of uveitis relapses/year, ocular complications and therapy and visual acuity, have reported. The validation procedure included the assessment of sensitivity, specificity and efficiency of previously published statistical model (Zulian et al. J Rheumatol 2002; 29: 2446-2453) in a new inception cohort of patients during a short length follow-up. Results: Sixty patients with JIA, followed at 14 paediatric rheumatology-ophthalmology centres in Italy, entered the study. The mean age at arthritis onset was 4.4 years (range 1.2-15.8 years), and the mean interval time between arthritis and uveitis onset was 1.8 years (range: 0.0-14.2 years). After the first AU, patients, followed for a mean of 3.2 years, had a mean of 2.9 uveitis relapses. Twenty-two patients (36.7%) presented at least one complication. Using a probability cut-off value = 0.7, the statistical model revealed 80% sensitivity, 58% specificity and 65% efficiency. Conclusion: The time interval between arthritis and uveitis onset resulted as the main predictor of severe course uveitis in JIA. The statistical model was able to predict the development of a severe course in 8 of 10 patients.