Effects of certain insecticides i.e. Coragen, Nomolt, Ekio and Magic smart with two species of entomopathogenic nematodes, Steinernama carpocapsae and Heterorhabdits bacteriophora were tested against cotton leaf worm Spodoptera littoralis. All tested insecticides caused less mortality to the tested entomopathogenic nematodes. Magic Smart significantly surpassed other insecticides causing the mortality of 11.6 and 13.8 % to the entomopathogenic nematodes S. carpocapsae and H. bacteriophora opposite to Coragen that caused slight mortality, 2.5 and 4.4%, respectively and didn't differ significantly than the check.  Nomolt and Ekio gave mortality of 5.4 and 8.8 % to S. carpocapsae as well as 8.8 and 12.0 % to H. bacteriophora respectively. These results show that the used insecticides have less effect on entomopathogenic nematodes specially S. carpocapsae. The entomopathogenic nematode S. carpocapsae exposed to Coragen, Nomolt, Ekio and Magic smart  gave 92.5, 85.0, 80.0 and75.0 % mortality to cotton leaf worms 5^th larval instar, respectively. The entomopathogenic nematode H. bacteriophora exposed to Coragen ,Nomolt, Ekio and Magic smart gave 83.4, 77.2, 71.0 and 60.6 % mortality % of S. littoralis, respectively.  Joint effect of insecticides and entomopathogenic nematodes  show that the mixture between S. carpocapsae with each of Coragen, Nomolt, Ekio and Magic smart at the quarter lethal concentration (LC_25s) per each gave synergism, synergism, additive and additive effects, respectively. As while H. bacteriophora mixed at the LC₂₅ with the LC_25s of Coragen, Nomolt, Ekio and Magic Smart attained synergism, additive, additive and additive effects, respectively.