The first studies involving the interstitial metazoan community of the Bahia Blanca Estuary started in 2007. Since then, three species of harpacticoid copepods and three species of nematodes have been described, and numerous species of turbellarians, as well as tardigrades and kinorhynchs, have been registered living in the intertidal sediments of the estuary. There is also an extensive documentation of other meiofaunal taxa that remains undetermined, due to the lack of trained taxonomists and the complexity of their systematics. Nevertheless, the study of the meiofauna was not restricted to the taxonomic aspects, and valuable information has been obtained in order to characterize the microscopic benthic community in this particular ecosystem, especially regarding the intricate relationships between taxa and their relation to the environment and associated abiotic factors. These surveys are, although still scarce, of high value, since specialists have been increasingly using the meiofauna as a bioindicator of the environmental quality on coastal marine systems. This contribution reveals many species new to science suggesting that the meiofaunal biodiversity of the Bahia Blanca Estuary remains underestimated.