Three occurrences of thegoby Gobius (Macrogobius) cruentatusin the southwestern region of Ireland are recorded. This species had previously been recorded as far north as southern Biscay. The range of the species is discussed, a full description of the three Irish specimens, and details of its distinguishing features are given. A key to the British species of the genusGobiusis given. The discussion compares the occurrence of this species with the distribution of other Lusitanian fishes and invertebrates on the Irish coast.