Objective To describe the pattern of cognitive impairment among children and adolescents with multiple sclerosis (MS) according to the International Pediatric MS Study Group criteria. Methods We analyzed cognitive performance using the computerized neuropsychological battery (GAB, NeuroTrax) in 20 patients with juvenile MS, mean+SD age at disease onset 13.4+2.8 years (range 9–16 years), 10 females, 10 males within 1 year from diagnosis. The GAB assesses performance across an array of cognitive domains including: memory, executive function, visual spatial perception, verbal function, attention, information processing speed, and motor skills with a combined global cognitive scoring (GCS). Results The mean GCS in the juvenile MS group was 93.7 (below the mean for age and education norms), and similarly decreased performance was observed in all domains as follows: memory (92.1) and specifically non-verbal memory (90.7), executive function (94.5), visual spatial perception (90.7), verbal function (88.4), attention (97.4), information processing speed (93.6), and motor skills (100.1). Conclusion Cognitive performance was decreased in children and adolescences with MS already during the first year from disease onset. The most impaired domain was verbal function suggesting targeted intervention should be early employed.