The prevalences of helminth parasites found on red foxes collected in two different habitats of the Ebro Valley, in north-eastern Spain were compared. Twenty helminth species, including one trematode, six cestodes, 12 nematodes and one acanthocephalan were found. Metorchis albidus, Uncinaria stenocephala and Dirofilaria immitis were more prevalent in the irrigated lands close to the main rivers of the study area, whereas Trichuris vulpis and Pterygodermatites affinis showed higher prevalences in the semiarid stepparian habitat. Habitat characteristics need to be considered when surveying helminths over large geographical areas. The study shows that in the Ebro Valley the fox constitutes a reservoir host for several helminth species that are parasites of the domestic dog or the wolf, or may have importance as zoonoses.