Abstract There are reports in which multiple sclerosis (MS) seems to be associated with abnormalities in selenium (Se) metabolism and erythrocyte glutathione-peroxidase (GSH-px) activity. Ordinary experimental allergic encephalomyelitis (EAE), which reflects some features of human MS, was induced in guinea pigs maintained with high, low and normal levels of Se in the diet. Evidence was obtained to indicate the following results: 1. (i) a direct correlation between dietary Se levels and whole blood Se levels. 2. (ii) Erythrocyte GSH-px activity was not found to be correlated with the blood Se content. 3. (iii) The animals fed with low or normal levels of Se showed the same survival rates and developed EAE in a similar way and percentage. 4. (iv) The animals fed with high non-toxic levels of Se showed a high incidence of death and some developed EAE with a subacute course, when compared with the other experimental groups. The results are discussed on the basis of findings in the literature.