An updated checklist of the polychaete species described for the Mexican Pacific and an historic review of their study are presented. The taxonomic list includes nomenclature references, data of the type locality and synonyms based on systematic revisions. In the study area, 313 species of polychaetes and 21 genera have been described, of which 278 species are currently valid. Several descriptions (28%) of the valid species failed to indicate the habitat of the type locality. The remaining 199 valid species were described for a large variety of habitats: algae (11 species), mangroves (2), hard bottoms (22), soft bottoms (continental shelf = 65 species; deep sea = 78 species), hydrothermal vents (17), and others (parasites, larval planktonic forms, epitokes) (4). The species descriptions for the Mexican Pacific can be divided into four main periods: the first, during the 1910s, includes mainly Chamberlin's studies of deep sea fauna. The second, in the 1940s, comprises studies carried out by Rioja (intertidal zone) and Hartman (including specimens from the Allan Hancock Foundation collection). The third period began around the 1970s when Fauchald's studies were published and 77 currently valid species were described for western Mexico. The fourth period began in the 1980s and continues to date, being characterized by descriptions of species done mainly by Mexican scientists. The differences in the number of species described during each period and for the different regions of the Mexican Pacific are directly related to the sampling effort carried out along these coasts.