OBJECTIVE To evaluate cognitive function in adult patients with juvenile idiopathic arthritis (JIA) and associated factors. METHODS We performed a cross-sectional observational study of adult patients with JIA and a healthy control group (no inflammatory diseases) matched for age, gender, and educational level. Cognitive function was assessed using Wechsler Adult Intelligence Scale-III. The cognitive domains measured were attention/concentration, verbal function, visuospatial organization, working memory, and problem solving (Similarities). Other measures included clinical-epidemiological characteristics, comorbid conditions, and treatment. We performed a descriptive bivariate analysis and logistic regression to identify factors associated with visuospatial involvement. RESULTS The study population comprised 104 subjects (52 with JIA and 52 healthy controls). Patients with JIA had poorer results for visuospatial function, with a lower median scaled score on the Block Design test (5.0 [4.0-8.0] vs 8.0 [5.0-10.0]; P = .014). The number of patients with scaled scores below the average range (<8) in visuospatial organization was significantly greater in the JIA group (67.3% vs 40.4%; P = .006). The multivariate analysis revealed time since diagnosis (odds ratio [95% CI], 1.03 [1.01-1.06]), inflammatory activity according to Juvenile Arthritis Disease Activity Score 27-joint count (1.94 [1.01-3.75]), and educational level (0.28 [0.08-0.94]) to be factors associated with visuospatial function. CONCLUSIONS Cognitive function in adult patients with JIA is poorer than in healthy controls at the expense of visuospatial function. Visuospatial function in JIA patients was inversely associated with disease duration, inflammatory activity, and lower educational level.