This research included taxonomic study of the larvae of three species belonging to three genera of flies of family Oestridae (Diptera), that causing myiasis in domestic animals in Wasit province. The study included the center of the province, and arrondissementes and districts areas affiliate (Alhayy, Badrah , Numaniya arrondissementes , Sheikh Saad districts and Albesrukih region ) . They are Hypoderma lineatum (DeVillers), Oestrus ovis Linnaeus and Cephalopina titillator Clark. Taxonomic keys are designed to isolate the genus, as well as its species, depending on the structure of the Cephalopharyngal skeleton, mouth hook and posterior spiracales, the collection of these species, the type of the host and the history of combining areas were reported. Larvae were collected from live animals, and the injury as an essential part of the complete life cycle. The sheep were more susceptible to injury of myiasis followed by cows and camels. The results showed the presence of eleven case of larvae of Oestrus ovis in sheep in the center of the province, two in Albesrukih region , two cases in the arrondissementes of Badrah , one case in each of Numaniya arrondissementes and Sheikh Saad districts , larvae of Hypoderma lineatum in cows in each of the center of the province , Alhayy arrondissementes and Albesrukih districts . Two cases of myiasis recorded of larvae Cephalopina titillator in the camels in the center of the province.