The frequency of blood-retina barrier (BRB) and blood-brain barrier (BBB) alterations was studied in 20 cases of Multiple Sclerosis (MS) (12 relapsing and 8 chronic-progressive). BBB impairment was found in 7 out of 20 patients (35%), 3 of whom had the chronic-progressive form of the disease. Alterations to BRB were found in 9 out 20 cases (45%): 2 out 12 (17%) of the relapsing cases and 7 out 8 of the chronic-progressive cases (87.5%). BBB impairment was found in 3 of the 9 cases (33%) with BRB alterations. Our findings indicate that BRB and BBB alterations do not occur simultaneously. We propose that the higher frequency of BRB alterations in chronic-progressive MS may be a sign of persistent antigenic stimulation.