A study was conducted to determine the species composition of fruit flies attacking mangoes and, the extent of mango fruit losses in selected areas of eastern Ethiopia. Fruit flies were collected using two methods; rearing from mango fruits and trapping with the use of Para pheromones. Six species of Tephritidaewere reared from mango fruits:Ceratitis fasciventris, Ceratitiscosyra, Bactroceracucurbitae, Dacusbivittatus, Ceratitisquinaria and Ceratitiscapitata. 83.1 %, 12.8%,. 2.7%, 0.7 %, 0.4 % and 0.21%, respectively. Nine fruit flies species, four of the genus Ceratitis, (C. cosyra, C. quinaria, C. capitataandC. fasciventris), three of Dacus(D.bivittatus, D. telfairaeandD. apoxanthu), and two of Bacterocera(B. invadens and B. cucurbitae),were collected using different parapheromones (Methyl eugenol, Cuelure, 3Component lure, Trimedlure and Terpinyl Acetate)from mango farms in eastern Ethiopia. Using pheromone traps three new fruit fly species were identified. Out of all species Ceratitisfasciventris were dominant followed by Ceratitiscosyra and Dacusbivittatus. All species has no relation with altitude. The extent of mango infestation on the average ranged 21 to 35% in different locations of Eastern Ethiopia. The overall mean percentage of mango losses is 30.4%.