The Vietnamese Mekong Delta has undergone much anthropogenic change in the last 100 years, and few areas of natural or semi-natural habitat remain. Despite the likely consequent loss of biodiversity, little documentation exists about the region's avifauna at any time in its history. Here, we present a review of the avifauna of the Vietnamese part of the Mekong delta based on various surveys and other fieldwork carried out since 1988, and an assessment of the few earlier data that were available. A total of 247 species has been recorded from the Vietnamese delta since 1988. Most pre-war data are now considered to be of uncertain validity. Some 50% of the species recorded since 1988 are dependent on wetlands. Of these, 20 are listed as globally threatened or Near Threatened. The delta supports, or is likely to support, internationally important numbers of 21 species of waterbird, including two threatened and three Near Threatened species. Annotations are provided for records of globally or regionally threatened species; for those species for which the Mekong Delta holds internationally important numbers; and those for which records described herein constitute range extensions. Information on the avifauna of the Mekong Delta presented here suggests it is of regional and global importance for the maintenance of wetland biodiversity.