As oligodendrocytes have binding sites for excitatory amino acids (glutamate, aspartate, serine, etc.), a role of these molecules in demyelinating disorders is possible. We measured the levels of amino acids in the cerebrospinal fluid (CSF) of patients with multiple sclerosis in comparison with CSF obtained by myelography from patients with lower back pain. There were no significant differences in the CSF concentrations of these amino acids between the two groups. Normal concentrations of excitotoxins do not exclude the role of these molecules in demyelinating disorders.