Neohelice granulata inhabits estuarine and protected coastal areas in temperate regions, and is the most dominant decapod crustacean in the Bahía Blanca estuary. The population structure was studied during a year in a SW Atlantic salt marsh located in the Bahía Blanca estuary, Argentina. Crabs were sampled monthly from August 2010 to July 2011. The maximum observed density was 39 crabs/m2 in February and 70 burrows/m2 in May. The maximum carapace width (CW) in males was 32 mm and 27.5 mm in females. Medium size crabs were between 16 and 20 mm CW. Significantly smaller sized crabs were observed at the lower intertidal regions (p