OBJECTIVE: To evaluate the frequency of chronic anterior uveitis in patients with juvenile idiopathic arthritis and its association with the presence of antinuclear antibodies. PATIENTS AND METHODS: We retrospectively studied 72 patients with juvenile idiopathic arthritis. All of them were submitted to slit-lamp examination of the anterior chamber at diagnosis. Both antinuclear antibodies and rheumatoid factor were determined. Patients with positive results for antinuclear antibodies were evaluated every three months and those with negative results were assessed every six months. RESULTS: Forty patients were male (55.5%) and 36 were Caucasoid (50%). The mean age at the onset of juvenile idiopathic arthritis was 6.4 years (range = 1 to 14 years) and the mean age at the beginning of the study was 10.4 years (1 to 19 years). According to the type of disease at onset, 32 were pauciarticular (44.4%) (17 boys and 15 girls), 30 were polyarticular (41.6%) (17 boys and 13 girls) and 10 were systemic (14%) (6 boys and 4 girls). We observed chronic anterior uveitis in five patients (6.5%) (mean age = 11.4 years). Among them, four (80%) had pauciarticular juvenile idiopathic arthritis at disease onset (three girls with type I juvenile idiopathic arthritis and positive antinuclear antibodies and one boy with type I juvenile idiopathic arthritis and negative antinuclear antibodies) and one girl with polyarticular juvenile idiopathic arthritis (negative antinuclear antibodies and rheumatoid factor). In this group, the mean age at the onset of juvenile idiopathic arthritis was 5.1 years and the mean age of uveitis onset was 9 years. Antinuclear antibodies were positive in 3/5 patients (60%) with uveitis. Antinuclear antibodies were positive in 12% of the patients without uveitis (n = 67). Among the patients with uveitis, three had only one flare and the other two had four flares with cataract. The frequency of antinuclear antibodies was statistically higher in the patients with uveitis (P< 0.05). CONCLUSION: Although the incidence of uveitis in our study was lower than that reported in the literature, the frequency of uveitis was higher in females, in those with pauciarticular juvenile idiopathic arthritis and in patients with positive antinuclear antibodies.