AIM: To investigate extent and nature of visual pathways involvement in children with clinically isolated syndrome (CIS). METHODS: Forty-seven patients (age 11-17y) with CIS, which later proved to be multiple sclerosis (MS) onset, and 30 controls underwent visual evoked potentials (VEP) investigation within 12d from the appearance of the first signs of disease. Latency and amplitude of P100 peak were compared with normative data and between groups. RESULTS: In 58% patients, including those without signs of retrobulbar neuritis, significant slowing of conduction along the central visual pathways (P100 latency lengthening) is seen. P100 amplitudes drop (signs of axonal damage) are registered less frequently (29% cases). CONCLUSION: The results indicate that visual pathways are often affected in the MS onset; mostly demyelination signs are seen. Despite MRI significance for MS diagnostic, VEPs proved to be still effective in early diagnosis of MS in children.