The state of Oaxaca in southern Mexico harbors the highest faunistic and floristic biodiversity of the region; however, to date, research effort has focused on terrestrial flora and fauna. Despite this bias, there is a large amount of dispersed information regarding the coastal and marine biodiversity of Oaxaca. The present study aimed to: 1) update and synthesize existing information to improve understanding of coastal and marine biodiversity; and 2) provide a baseline for future biodiversity studies in Oaxaca. The review of 198 references about Oaxaca's flora and fauna produced 2, 157 species records, from 15 taxonomic groups (Division, Phyla or Class). Nevertheless, knowledge about the fauna and flora of Oaxaca remains scarce compared to other regions, such as the Gulf of California. Additionally, floristic and faunistic knowledge is heterogeneous among the taxonomic groups; for instance, 242 (11 .2 °/o) species represent macroalgae, three invertebrate groups (annelids, crustaceans and mollusks) represent about 44.0% (949 species) of all species recorded, while the vertebrates are represented by 762 species (35.3°/o). Similarly, many invertebrate groups recorded in adjacent regions have not yet been recorded on the Oaxaca coast, including some platyhelminthes, rotifers, nematodes, oligochaetes, sipunculids, echiurans, tardigrades, pycnogonids, some crustaceans, brachiopods, chaetognaths, ascidians and cephalochordates. The study of the marine flora and fauna is far from finished; additional effort is required to complete the marine biodiversity inventory of Oaxaca.