Twenty one cases of epithelial cysts in the central nervous system including six colloid cysts of the third ventricle, eight Rathke's cleft cysts in the sella, two enterogenous cysts in the posterior fossa, two epithelial cysts in the spinal canal and three neuroectodermal cysts in the cerebrum were examined immunohistochemically for expression of intermediate filamentous proteins-simple type, stratified type and skin type cytokeratins and GFAP. Colloid cysts of the third ventricle. Rathke's cleft cysts in the sella and epithelial cysts in the spinal canal expressed complexed type cytokeratins while enterogenous cysts and neuroectodermal cysts showed only simple type cytokeratins. In addition, several Rathke's cleft cysts demonstrated skin type differentiation and expressed GFAP in occasional lining cells. The characteristic composition and distribution of cytokeratins in various kinds of epithelial cysts in the central nervous system are demonstrated and discussed with regards to their origins.