Objective To investigate the role of the adhesion molecule CD44 in the pathogenesis of experimental autoimmune encephalomyelitis (EAE).Methods A total of 20 rats were randomly divided into EAE group and control group. Crude myelin basic protein (MBP) antigen (0.2 mL/100 g) was subcutaneously injected into the hind foot of the rats in the EAE group to establish an EAE model, and then disease onset and pathological manifestations were observed. Immunohistochemistry was used to measure the content of CD44 in brain tissue for both groups.Results Disease onset was not observed in the control group, while this was observed in the EAE group with varying degrees. Observation under a light microscope after HE staining showed no abnormalities in the brain and spine of the rats in the control group, while congestion of small blood vessels, inflammatory cell infiltration around small veins, and demyelination in white matter were observed in the EAE group. Immunohistochemistry showed that no CD44-positive cells were found in the brain and spinal tissues of the rats in the control group, while a large number of CD44-positive cells were observed at the junction of grey matter and white matter in the central nervous system.Conclusions There is high expression of the adhesion molecule CD44 in the rat model of EAE, which may promote the onset of EAE.