We determined serum levels of ascorbic acid, beta-carotene, retinol and alpha tocopherol and lipid peroxidation (as estimated by thiobarbituric acid reacting substances (TBARS) generation) in 24 multiple sclerosis (MS) patients and 24 healthy sex- and age-matched person as control. The levels of four antioxidant vitamins were significantly lower in MS patients compared to controls (p < 0.05). TBARS levels were significantly higher in the patients of MS compared to the controls (p = 0.001). In MS patients, the levels of beta-carotene, alpha tocopherol and ascorbic acid correlated significantly with each other (r(2) = 0.689 - 0.779). It appeared that there was inverse correlation between the serum levels of ascorbic acid or beta-carotene, but not of alpha tocopherol or retinol, and TBARS levels in MS. The present study indicates that antioxidant vitamins (alpha tocopherol, beta-carotene, retinol and ascorbic acid) are decreased in sera of MS patients during an attack, and that this decrease may well be dependent on the increased oxidative burden as reflected by lipid peroxidation products. The role of antioxidant vitamin supplementation in prevention and/or treatment of MS remains to be explored.