Angiostrongylus cantonensis causes eosinophilic meningitis or meningoencephalitis, yet little is known about demyelination caused by this parasite. To define the course of demyelination caused by A. cantonensis, we analyzed the expression of myelin proteins including myelin-associated glycoprotein (MAG), myelin basic protein (MBP), myelin-associated oligodendrocytic basic protein (MOBP), and proteolipid protein (PLP) in brain and cerebrospinal fluid (CSF)-like fluid of infected and uninfected BALB/c mice. In A. cantonensis-infected mice, the expression of MAG, MBP, MOBP, and PLP mRNAs in brain tissue was decreased, while expression of the corresponding proteins was significantly increased in CSF-like fluid. Light microscopy revealed perivascular infiltrates in the brain during meningoencephalitis, suggesting that the cause of demyelination in angiostrongyliasis was immune system attack on the oligodendrocytic myelin sheath and subsequent release of myelin proteins into the CSF. Thus, intracerebral myelin breakdown in angiostrongyliasis may be a response to inflammatory mediators and the cause of increased myelin proteins in the CSF-like fluid.