More than 350 shells and specimens of seguenzioidean gastropods were found in samples from eight campaigns exploring the outer continental shelf and slope off Galicia (NW Spain) in the depth range 171-5314 m. They belong to 17 genera and 30 species. The most frequent species in the samples were Anekes paucistriata, A. sculpturata, Putzesia wiseri and Danilia tinei. Four of the species are identified with doubts, and three more only to the genus level. Taxonomic problems involving these doubtful species are commented. One species in Eudaroniidae is described as new: Eudaronia diazagrasi n. sp.