Trematoda Rudolphi, 1808
Accacoeliidae Looss, 1912
Aerobiotrematidae
Albulatrematidae
Aphanhysteridae
Areobiotrematidae
Arnolidae
Azygiidae Lühe, 1909
Bathycotylidae Dollfus, 1932
Bivesiculidae Yamaguti, 1934
Bothrigastridae
Cylindrorchiidae
Dictysarcidae Skrjabin & Guschanskaja, 1955
Didymozoidae Monticelli, 1888
Halipegidae
Hemiuridae Looss, 1899
Hirudinellidae Dollfus, 1932
Lampritrematidae Skrjabin & Guschanskaja, 1955
Lobatovitelliovariidae
Mabiaramidae
Oesophagicolidae
Pelorohelminthidae
Prosogonotrematidae
Ptychogonimidae Dollfus, 1937
Sclerodistomatidae
Sclerodistomidae Odhner, 1927
Syncoeliidae Dollfus, 1923
Tetrasteridae
Transversotrematidae Witenberg, 1944
Typhlocoelidae Harrah, 1922
Waretrematidae
