We found that mMOG-35-55 peptide was strongly immunogenic and induced moderately severe chronic experimental autoimmune encephalomyelitis (EAE) with white matter lesions after a single injection in Freund's complete adjuvant followed by pertussis toxin. hMOG-35-55 peptide,which differs from mMOG-35-55 peptide by a proline for serine substitution at position 42, was also immunogenic, but not encephalitogenic, and was only partially cross-reactive with mMOG-35-55.