A taxonomic revision of Brazilian Diplazium recognized 28 species. The majority of these species are associated with preserved moist forest environments. The monographic study of Diplazium, as suggested by several authors over the last 30 years, has been difficult due to the large number of widely distributed taxa. Nine species are endemic to Brazil: Diplazium adnatum, D. brachycarpum, D. fimbriatum, D. leptochlamys, D. leptocarpon, D. longipes, D. mickelii, D. mutilum, D. tamandarei. We present an identification key for species with their descriptions, and illustrations. Twenty one lectotypes are also listed.