The European mink (M. lutreola) and the American mink (M. vison) are riparian mustelids inhabiting Spain. During the last few decades, M. lutreola populations have declined almost everywhere, but, since being introduced in Europe, the American mink has become wide spread there. The present study presents the first comprehensive helminthological data of both mink species in Western Europe and analyses the possible cross-transmission of some pathogenic helminths between neighbouring Spanish populations of both mustelids. One hundred and forty specimens (28 M. lutreola and 112 M. vison) from several Spanish zones were analysed. A total of thirteen helminth species were found: Metorchis bilis, Parametorchis sp., Pseudamphistomum truncatum, Euryhelmis squamula and Apophallus donicus (Trematoda), Taenia martis and T. tenuicollis (Cestoda), Aonchotheca putorii, Strongyloides mustelorum, Molineus patens, Crenosoma melesi and Aelurostrongylus pridhami (Nematoda), and Centrorhynchus ninnii (Acanthocephala). The helminth fauna of M. lutreola was qualitatively and quantitatively richer than that of M. vison. This fact was particularly evident amongst digeneans with four species (M. bilis, Parametorchis sp., P. truncatum and A. donicus) exclusively present in M. lutreola. Twenty-five M. lutreola individuals were infected with parasitic worms (89.3%). In contrast, less than half (41.1%) of the American minks analysed were infected by helminths. The helminth fauna of both European and American minks in Spain are compared with those of both mustelids in some epidemiological and pathogenic aspects of the helminth fauna of both mink species that might act as regulatory factors over the Spanish population of M. lutreola.