The fish and invertebrates community structure in the Sabancuy estuary was analyzed in two seasons and 14 sampling stations (13 along the estuary and one in the marine adjacent coast). No significant differences were found between seasons. The environmental frame defines two zones within the estuary, the first extends from the access highway to Sabancuy town until the Pujo mouth in the west; the second from the bridge to the estuary head in the east. The most abundant invertebrates were mollusks (51.8% of the total), in biomass the crustaceans dominated. The fish included 21 families and 33 species; the most abundant were Gerridae, Scianidae, Sparidae, Lutjanidae and Ciprinodontidae. The highest diversities of both communities correspond to the central part of the estuary. These communities include three sections with notable differences in faunal distribution: one is influenced by the exit to Terminos lagoon, the secondary in the estuary head and a third is in a transition zone defined by the proximity of the town access bridge. The ecological organization suggests a strong division caused by the bridge, both sides are scarce in habitats and nutrient resources and this is reflected in the low species counts. ; La estructura comunitaria de peces e invertebrados en el estero de Sabancuy fue analizada en dos temporadas y 14 estaciones de muestreo (13 a lo largo del estero y una en la costa marina adyacente). No se encontraron diferencias significativas entre las temporadas. El marco ambiental define dos zonas dentro del estero, la primera va de la carretera de acceso al pueblo de Sabancuy hasta la boca del Pujo en el oeste; la segunda del puente a la cabeza del estero en el este. Los invertebrados más abundantes fueron los moluscos (51.8 % del total) y en la biomasa los crustáceos. Los peces registraron 21 familias y 33 especies. Las familias más abundantes fueron Gerridae, Scianidae, Sparidae, Lutjanidae y Cipinodontidae. Las diversidades más altas de ambas comunidades corresponden a la parte central del estero. ...