Experimental allergic encephalomyelitis (EAE) is one of the experimental models of human demyelinating diseases and recently is regarded also as useful model for studying cell-mediated autoimmune diseases. Because of the possibility of induction of systemic changes in this model, we investigated enzymatic changes in serum and main organs of the diseased animals, including brain, spinal cord, limb muscle, heart muscle, spleen, liver and kidney. The enzymes measured consisted of 7 aminopeptidases, 5 endopeptidases, 3 glycosidases, creating kinase, phosphatase and esterase. Significant changes of many enzymatic activities occurred in all the organs tested in 1 to 2 weeks after the administration of EAE antigen, myelin basic protein (MBP). Interesting correlations of the pattern of enzymatic changes were seen among most of the organs tested. Those patterns changed in the course of the 2 weeks and there remanied marked changes characteristic for each organ. This model may represent some type of systemic autoimmune diseases.