This paper presents a synoptic revision of the genus Lastreopsis Ching (Dryopteridaceae) in Madagascar. A new identification key is presented, along with new distribution maps. The presence of L. barteriana (Hook.) Tardieu, an African species, is indicated for the first time. Three new species are described: 1) L. coriaceosquamata Rakotondr. resembles L. boivinii (Baker) Tardieu but can be distinguished by differences in the morphology of the scales present on its rhizome and petiole base, which is brownish black, coriaceous, flat, and appressed; 2) L. manongarivensis Rakotondr. can be easily distinguished by its upright rhizome covered with red, membraneous scales; and 3) L. fidelei Rakotondr. has median sori similar to those of L. currorii (Mett. ex Kuhn) Tindale but can be distinguished by having non-gemmiferous fronds, median pinnae that are 1-pinnate-pinnatifid and indusia with entire margins. Two African species, L. currorii and L. subsimilis (Hook.) Tindale, have been cited in the literature as occurring in Madagascar, but the material from there differs clearly from the type specimens, and these taxa are no longer thought to occur in Madagascar. The type of Lastreopsis hornei (Baker) Tindale from the Seychelles, is fragmentary, and this name is treated as “insufficiently known”. Finally, a lectotype is designated for Nephrodium granulosum Baker, a synonym of L. boivinii.