This paper discuss the vertical and horizontal distribution of the marine isopod Rocinela signata Schiödte & Meinert, 1879, along Brazil. Published records and new data gathered in recent years were used. The species, widely distributed along Brazil, has its most southern limit of occurrence considerably extended to off State of Santa Catarina (27º08'S, 48º11'W) . It is typically a shelf species. So far it was recorded off Brazil at a maximum depth of 73 m, while particularly in southern Brazil at 53 m. The species has been collected free living on the bottom or as a fish parasite, and a few times has been reported attacking and sucking swimmers. Available data suggest any host specificity. R. signata seems a facultative and not an obligate fish parasite.