During a survey of the decapod fauna of the sublittoral region of the estuaries of the State of Rio Grande do Norte, a high percentage of infection on Hexapanopeus schmitti Rathbun by a rhizocephalan pararite was observed in one of the estuaries. Morphological changes associated with the parasitism were clearly manifested by the host. Single as well as multiple infections were also recorded. Hosts between 3.1 mm and 8.0 mm carapace width were observed to be infected, though largest percentage of parasitism occured within the size range of 5.1 and 7.0 mm.