A new species of parasitic nematode, Philometroides barbi sp. nov., is described from subgravid and mature females parasitic in the Mediterranean barbel Barbus meridionalis Risso (Pisces, Cyprinidae) in France, Serbia and Slovakia. Mature females were recorded under the serosa of the host's swimbladder, whereas large subgravid females (body length 62.0-80.9 mm) were found in the abdominal cavity. One small subgravid specimen (body length 10.4 mm) was recovered from the fin. The new species differs from other congeners in possessing four conspicuously large 'caudal lobes; from many species it can be also differentiated by the distribution of cuticular bosses and by the structure and length of the oesophagus. P. barbi is the third species of Philometroides known from European freshwater fishes and the only representative of this genus in barbels (Barbus spp.).