Growing evidence has demonstrated that microplastics (MPs) are available for a wide range of marine organisms, with filter-feeding bivalves and crabs being especially vulnerable. The crab Neohelice granulata is considered a key and structuring species in the Bahía Blanca Estuary (BBE) (SW Atlantic) and its ecological role makes this species especially vulnerable to several pollutants. In this study, male specimens of N. granulata and water samples were collected at three sites in the BBE for the presence of MPs. Different types of MPs were found in all the crabs and the water column samples, although the most frequent were fibers <500–1500 μm, mainly blue. This is the first study to identify MPs in the gills and digestive tract of N. granulata. Moreover, gills presented higher total abundances of MPs than the digestive tract, which suggests that in this case the main uptake of MPs would be by adherence to the gills. •Microplastics (MPs) were identified in Neohelice granulata and in the water column from the Bahía Blanca Estuary.•The most frequent MPs were blue fibers <500–1500 μm•Gills presented higher abundances of MPs than the digestive tract.•In N. granulata the main uptake of MPs would be by adherence to the gills.