This is part of a series of papers (Tavares, 1991a, 1991b, 1992a, 1992b, 1992c) reviewing the Cyclodorippidae Ortmann, 1892, and Cymonomidae Bouvier, 1897, of the world. It contains a review of all the Cyclodorippidae from the Indo-West Pacific as well as one genus of Cymonomidae. This is a systematic approach preceding a more detailed study of the Cyclodorippoidea morphology and of the phylogenetic relationships within the superfamily. The present work was based upon large collections from the Indo-West Pacific (Madagascar, Japan, Vietnam, Philippines, Indonesia, Australia, Chesterfield Islands, New Caledonia, Loyalty Islands, and Wallis and Futuna Islands) carried out by the following French expeditions : MUSORSTOM 1-7, BIOCAL, CHALCAL 2, CORAIL 2, KARUBAR, LAGON, and SMIB 6. Also included is the material collected by the "Siboga" Expedition. 1899, "Albatross", 1908, the material collected by the Russian oceanographic ships "Orlik" in 1960 on the coast of Vietnam and "Vytiatz" on the west coast of Australia, two samples made by Raoul SERÉNE in Indonesia in during the RUMPHIUS I expedition in 1973 and RUMPHIUS IV in 1975, as well as collections made by the Australian ship "Soela" in 1984 on the north coast of Australia, and others made during the expedition CIDARIS I under the auspices of the James Cook University on the Great Barrier Reef. Additional material from the collections of The Natural History Museum (British Museum), London ; Museum of Comparative Zoology, Massachusetts ; Zoological Museum of Moscow University ; National Science Museum, Tokyo ; Northern Territory Museum of Arts and Science, Darwin ; Queensland Museum, Brisbane ; South African Museum, Cape Town ; National Museum of Natural History, Smithsonian Institution, Washington and Zoölogisch Museum, Amsterdam was also examined. Because of insufficient original descriptions, the re-examination of all type specimens [except for Tymolus truncatus (Ihle, 1916) which is apparently lost and Genkaia gordonae Miyake and Takeda, 1970] and most of the specimens cited in the literature, was required to properly establish the correspondence between species and the names introduced in the literature. Until now, seven genera (Tymolus, Corycodus, Xeinostoma, Genkaia, Krangalangia, Ketamia, and Cymonomus) and 23 species of Cyclodorippidae and Cymonomidae were known from the Indo-west Pacific. They are as follows : Cyclodorippidae : Tymolus japonicus Stimpson, 1858, T. uncifer (Ortmann, 1892), T. dromioides (Ortmann, 1892), T. similis (Grant, 1905), T. truncatus (Ihle, 1916), T. brucei Tavares, 1991, Corycodus disjunctipes (Stebbing, 1910), Xeinostoma eucheir Stebbing, 1920, Krangalangia rostrata (Ihle, 1916), K. spinosa (Zarenkov, 1970), Ketamia depressa (Ihle, 1916), Genkaia gordonae Miyake and Takeda, 1970. Cymonomidae : Cymonomus valdiviae Lankaster, 1903, C. andamanicus Alcock, 1905, C. indicus Ihle, 1916, C. trifurcus Stebbing, 1920, C. japonicus Balss, 1922, C. curvirostris Sakai, 1965, C. aequilonius Dell, 1971, C. bathamae Dell, 1971, C. delli Griffin and Brown, 1976, C. umitake Takeda, 1981, C. hakuhoae Takeda and Moosa, 1990. From this study : - Two new genera (Phyllotymolinum and Elassopodus) and 11 new species of Cyclodorippoidea are herein described : Cyclodorippidae : Corycodus merweae, C. decorus, Xeinostoma richeri, X. sakaii, Krangalangia orstom, Ketamia handokoi, K. limatula, K. próxima, Genkaia keijii, Phyllotymolinum crosnieri. Cymonomidae : Elassopodus stellatus.- Two species are resurrected : Corycodus bouvieri Ihle, 1916, from the synonymy of C. disjunctipes (Stebbing, 1910) and Krangalangia spinosa (Zarenkov, 1970) from the synonymy of A", rostrata (Ihle, 1916).- Four lectotypes are designated here for the following species : Corycodus disjunctipes, Xeinostoma eucheir, Krangalangia rostrata, and Ketamia depressa. Presently, a total of 9 genera (7 Cyclodorippidae and 2 Cymonomidae) and 34 species (22 Cyclodorippidae and 12 Cymonomidae) are known from the Indo-West Pacific. All these species are studied here except those belonging to the genus Cymonomus which will be treated in a future publication. Keys for families, genera and species are provided as well as illustrations for all species.