Laboratory experiments were performed to evaluate the pathogenic and lethal effects of the entomopathogenic nematodes Hb (Heterorhabditis bacteriophora Poinar) and Sc (Steinernema carpocapsae All strains) on the full grown larvae, newly formed pupae and seven days old adults of the peach fruit fly, Bactrocera zonata and the cucurbit fly, Dacus ciliatus. Mortality rates ranged from 9.3 to 42.7%, 12.7 to 52.3 % for the full grown larvae of both B. zonata and D. ciliatus treated by Sc nematode, respectively, and from 67.3 to 100%, from 46.3 to 100% for the full grown larvae of both B. zonata and D. ciliatus treated by Hb nematode, respectively, whereas mortality rates of pupae ranged from 2.7 to 32.7% for the pupae of B. zonata treated by Sc nematode, from 1.7 to 23.3% for the pupae of D. ciliatus treated by Sc nematode , from 12.7 to 51.7 % for the pupae of B. zonata treated by Hb nematode and from 6.3 to 39.3 % for the pupae of B. zonata treated by Hb nematode. Furthermore, the mortality rates varied from 35.0 to 78.7% , 7.7 to 50.3% for 7 days old adults of both B. zonata and D. ciliatus treated by Sc nematode, respectively, 41.7 to 90.3 and 17.0 to 67.7 % for 7 days old adults both B. zonata and D. ciliatus treated by Hb nematode, respectively. LC50 and LC90 values were 325.3, 286.2, 1718.6 and 1650.0 IJs/ cm2 for larvae of B. zonata and D. ciliatus treated with Sc nematode, 28.8, 56.7, 167.2 and 156.1 IJs/cm2 for larvae of B. zonata and D. ciliatus treated with Hb nematode, 540.2, 447.4, 1785.4 and 2009.8 IJs/ cm2 for pupae of B. zonata and D. ciliatus treated with Sc nematode, 235.0, 420.8, 1167.0 and 1941.5 IJs/ cm2 for pupae of B. zonata and D. ciliatus treated with Hb nematode, 116.8, 261.6, 319.3 and 375.0 IJs/ cm2 for adults of B. zonata and D. ciliatus treated with Sc nematode and 77.3, 196.7, 290.8 and 253.7 IJs/ cm2 for adults of B. zonata and D. ciliatus treated with Hb nematode, respectively. From the obtained results we can conclude that the entomopathogenic nematodes: Hb Heterorhabditis bacteriophora Poinar) and Sc (Steinernema carpocapsae All strains) were effective on the different stages of B. zonata and D. ciliatus , Hb nematode was more virulent than Sc nematode and the larvae and adults of B. zonata and D. ciliatus were more susceptible to the nematodes infection than the pupae.