We are reporting a case of Behçet's disease without vasculitis, but with acute neutrophilic inflammation which involved the brain and other organs. The patient exhibited waxing and waning neurological deficits which were unresponsive to treatment. The neuroradiologic findings simulated those of multiple sclerosis. The neuropathological examination revealed an acute, focal, though disseminated encephalitis involving the frontal lobe, internal capsule, basal ganglia, cerebellum, and brain stem. The acute inflammation consisted of a neutrophilic and eosinophilic infiltration of the perivascular spaces and parenchyma without evidence of vasculitis, fibrinoid necrosis, or thrombosis. Cultures and special stains for microbial organisms were negative. Ultrastructural examination revealed no viral structures or other microorganisms. In situ hybridization for Epstein-Barr virus (EBV), herpes simplex virus type I (HSVI), and cytomegalovirus (CMV) was negative. In this case, the lack of inflammation in the vessel walls points out that the necrotizing lesions in neuro-Behçet's disease need not be the result of vasculitis and superimposed thrombosis, but may occur as a result of primary, acute neutrophilic inflammation.