Contents: Introduction. Hisotrical review. Class trematoda. 1. Subfamily Bucephalinae Nicoll, 1914. Genus Bucephalus baer, 1826. Genus Bucephalopsis (Diesing, 1855) Yamaguti, 1958. 2. Subfamily Neoprosorhychinae Yamaguti, 1958. Genus Roparhynchus Gupta and Kumari, 1974. 2. Order Fasciolatidea szidat, 1936: 1. Suborder Echinostomata szidat, 1939. 1. Superfamily Echinostomatoidea faust, 1929. 1. Family Echinostomatidea poche, 1925: 1. Subfamily Singhiinae Yamaguti, 1958. Genus Singhia Yamaguti, 1958. 2. Superfamily Haploporoidea Nicoll, 1935 emend, Dollfus, 1952 emend. Mehra, 1961. 1. Family Haploporidae Nicoll, 1914. 1. Subfamily Megasoleninae manter, 1935. Genus Hapladena Linton, 1910. 1. Subfamily Waretrematinae belouss, 1954. Genus Carassotrema Park, 1938. Genus Saccoelioides szidat, 1954. Genus Haploporous Looss, 1902. Genus Lecithobotrys Looss, 1902. 2. Suborder Fellodistomata Singh, 1960. 1. Superfamily Fellodistomoidea Mehra, 1963. 1. Family Fellodistomidae Nicoll, 1913. 1. Subfamily Complexobursinae Yamaguri, 1971. Genus Complexobursa Osmarin and Mamaev, 1963. 2. Subfamily Antorchinae Yamaguti, 1958. Genus Faustula Poche, 1926. 1. Subfamily Monascinae Yamaguti, 1958. 3. Suborder Paramphistomata Nicoll, 1914. 1. Superfamily Paramphistomoideda Fischoeder, 1901. 1. Family Paramphistomidae Fischoeder, 1901. 1. Subfamily Cleptodiscinae skrjabin, 1949. Genus Neocladorchis Bhalerao, 1937. 2. Subfamily Heliostomatinae skrjabin, 1949. Genus Helostomatis (Fukui, 1929) Mac Callaum, 1905. 3. Subfamily Dadytrematinae Yamaguti, 1958. Genus orientodiscus Srivastava, 1938. Genus pseudoorientodiscus Agrawal and Sharma, 1991. 4. Subfamily Nicollodiscinae Skrjabin, 1949. Genus Nicollodiscus Srivastava, 1938. 5. Subfamily Caballeroinae Daveraj, 1972. Genus Caballeroia Thapar, 1960. 4. Suborder Opisthorchiata La Rue, 1957. 1. Superfamily Opisthorchioidea faust, 1929 Vogel, 1934. 1. Family Opisthorchiidae Braun, 1901. 1. Subfamily Opisthorchinae Looss, 1899. Genus Opisthorchis Blanchard, 1895. Genus Gomtia Thapar, 1930. Genus Thaparotrema Gupta, 1953. 2. Subfamily Gomtiotreminae Gupta, 1953. Genus Allogomtiotrema (Gomtiotrema Gupta, 1953) Yamaguti, 1958. 2. Family Hetrophyidae Odhner, 1914. 1. Subfamily Haplorchiinae Looss, 1899. Genus Haplorchoides Chen, 1949. 2. Subfamily Polyorchitrematinae Yamaguti, 1958. Genus Polyorchitrema Srivastava, 1939. 3. Family Cryptogonimidae Ciurea, 1933. 5. Suborder Plagiorchiata La Rue, 1957. 6. Family Lepocreadiidae Nicoll, 1934. 7. Family Opecoelidae stunkard, 1931. 8. Family Monorchiidae Odhner, 1911. 9. Family Asymphyllodoriidae. 10. Family Stomylotrematidae poche, 1926. Host parasite list. References.