Human-infecting digenetic trematodes are approximately 70 species which belong to 60 genera over the world. According to their habitat in the definitive hosts, they are classified as blood flukes (Schistosoma japonicum. S. mekongi, S. mansoni, S. haematobium, and S. intercalatum), liver flukes (Clonorchis sinensis, Opisthorchis viverrini, O. felineus, Metorchis conjunctus, Dicrocoelium dendriticum, Fasciola hepatica, and F. gigantica), lung flukes (Paragonimus westermani, P. heterotremus, P. skrjabini, P. skrjabini miyazakii, P. kellicotti, P. mexicanus, P. africanus, and P. uterobilateralis), and intestinal flukes (Metagonimus yokogawai, M. miyatai, M. takahashii, Heterophyes nocens, H. heterophyes, Haplorchis taichui, H. pumilio, H. yokogawai, Centrocestus formosanus, Echinostoma revolutum, E. ilocanum, E. hortense, Echinochasmus japonicus, E. lilliputanus, Artyfechinostomum malayanum, A. oraoni, Clinostomum complanatum, Eurytrema pancreaticum, Fasciolopsis buski, Gymnophalloides seoi, Neodiplostomum seoulense, Prosthodendrium molenkampi, Phaneropsolus bonnei, and Plagiorchis muris). The mode of transmission to humans include contact with cercariae contaminated in water (schistosomes) or ingestion of raw or improperly cooked fish (liver flukes, heterophyids, and echinostomes), snails (echinostomes and gymnophallids), amphibians, and reptiles (neodiplostomes). Praziquantel has been proved to be highly effective against most species of trematode infections except fascioliasis. Epidemiological surveys and detection of human infections are required for better understanding of the geographical distribution and endemicity of each trematode species.