EAE is a good model of autoimmune diseases and an approximate one of MS, particularly in its chronic recurrent and demyelinating forms. The antigenic target of EAE has recently been better defined: in different species, as well as within a given one, the encephalitogenic determinant, target of T effector cells, is located in different parts of the basic protein of myelin. The recognition of the relevant epitope is influenced by the genotype of the antigen presenting cells. By analogy, in MS, one can expect to find various target-antigens for the immune (autoimmune?) reactions that occur in the Central Nervous System of different patients, may be in correlation with HLA phenotype. The study of immunoregulatory processes in EAE suggests a possible role for suppressor cells and for variations in the capacity of interleukin-2 production. Similarly, in MS, variations in suppressor cell activities have been found in acute attacks. Finally, the possibility of "vaccinating" against EAE with attenuated encephalitogenic line cells, opens new interesting perspectives in the therapy of MS.