The name “trematode” has been originated from the word “trematos” meaning “pierced with holes.” Digenetic trematodes are very important parasites in the field of veterinary science. These trematodes occur in different organs of a wide variety of domestic and wild animals. Some digenetic trematodes pose a great threat to the livestock industry. In this chapter, the description of trematodes of veterinary importance has been given encompassing different aspects of trematodes, i.e., classification, distribution, discovery, hosts, site, morphology, biology, pathogenesis, diagnosis, treatment, and control.