Experimental autoimmune encephalomyelitis (EAE) is a demyelinating disease of the central nervous system (CNS) induced in rodents by activated CD4+ T cells specific for various myelin proteins such as myelin basic protein and proteolipid protein. The disease is characterized by breach of the blood-brain barrier, perivascular infiltration of leukocytes into the CNS, local inflammation and demyelination in the form of plaques. In this study, we evaluated the effect of administration of antibodies to two members of the beta 2 integrin sub-family of adhesion molecules, CD11a and CD11b, on the onset and progression of EAE. CD11a and CD11b are involved in cell-cell interactions leading to T cell and macrophage extravasation to inflammatory sites and T cell activation. Our results show that anti-CD11a antibodies could completely block the induction of EAE and anti-CD11b antibodies significantly delayed the onset and diminished the severity of clinical signs of EAE even when injections were initiated at the first appearance of clinical signs.