Trematoda Rudolphi, 1808
Allodiscocotylidae Tripathi, 1959
Allomicrocotylidae
Allopyragraphoridae Yamaguti, 1963
Anchorophoridae Bychowsky & Nagibina, 1958
Aviellidae
Axinidae Unnithan, 1957
Cemocotylidae
Chimaericolidae Brinkmann, 1952
Dactylocotylidae Brinkmann, 1942
Diclidophoridae Cerfontaine, 1895
Diclybothriidae Bychowsky & Gussev, 1950
Diplozoidae
Discocotylidae Price, 1936
Gastrocotylidae Price, 1943
Heteraxinidae Price, 1962
Heteromicrocotylidae Unnithan, 1961
Hexabothriidae Price, 1942
Hexostomatidae Price, 1936
Macrovalvitrematidae Yamaguti, 1963
Mazocraeidae Price, 1936
Megalonchidae
Microcotylidae Taschenberg, 1879
Neothoracocotylidae Lebedev, 1969
Octolabeidae Yamaguti, 1963
Plectanocotylidae Monticelli, 1903
Polystomatidae Gamble, 1896
Protomicrocotylidae Johnston & Tiegs, 1922
Pseudodiclidophoridae Yamaguti, 1965
Pterinotrematidae Bychowsky & Nagibina, 1959
Pyragraphoridae Yamaguti, 1963
Sphyranuridae Poche, 1926
