The present survey was carried out to investigate the prevalence of cardiopulmonary helminths in red foxes in Pyrenees area and to evaluate the role of foxes in the eco-epidemiology of these nematodes. Hearts and entire respiratory tracts were obtained from 87 foxes from Vall d'Aran region, Pyrenees, Catalonia, north-eastern Spain. The cardiopulmonary tracts were dissected, flushed and examined for nematodes using sedimented flushing water. Of the 87 examined foxes, 53 (61%) were positive for cardiopulmonary helminths. The identified nematodes were Crenosoma vulpis (44.8%), Eucoleus aerophilus (29.9%) and Angiostrongylus vasorum (3.4%). Statistical differences were observed only on comparing age and C.vulpis prevalence, with young foxes being more infected than adults. The high prevalence of cardiopulmonary nematodes suggested that red foxes may play an important role in their transmission and maintenance in the studied area.