Abstract: Objective To observe the therapeutic effect of monoamine oxidase (MAO) monoclonal antibody (mAb) for vaso-genic brain edema (VBE) in rats.Methods A total of 75 Wistar rats were randomized into non-edema, non-treated edema, sal ine-treated edema, mannitol-treated edema and MAO mAb-treated groups. Rat models of VBE were established by in-traperitoneal injection of phenylephrine in the l atter 4 groups. Brain water content in the gray and white matter was measured r espectively with a moisture analyzer, and the permeability of the blood-brain ba rrier (BBB) determined by Evan’s blue (EB) extravasation method.Results MAO mA b administration significantly reduced the brain water content in the gray and w hite matter as well as the permeability of BBB (P<0.01), Which was especially e ffective for the white matter, producing results comparable with those of the n on-edema group (P>0.05). MAO mAb markedly alleviated brain edema, with better de hydrat-ing effect on the white matter than mannitol (P<0.01), which reduced the water content of the brain gray and white matter undiscriminatingly and showed poor effect on the permeability of BBB.Conclusion The pathogenesis of BBB perme ability changes in VBE is related to the activity of monoamine oxidase, and MAO mAb has selective therapeutic effect on VBE, which is especially obvious on br ain white matter.