The toxicity of eighteen insecticides and their mixtures against adults of the cotton aphid Aphis gossypii Glovercollected from Menufia Governorate early in 2000 cotton season were investigated.      The results revealed that Meothrin was the first most toxic followed by the mineral oil Kz-oil then Karate. MTI-446 came next in its toxicity followed by Actara, Sumicidin, Baythroid, Confidor and the natural product Neemix. However, Selecron, Aphox and Marshal were the least toxic followed by all other OP compounds, and the insecticidal soap, M.Pede.      The joint action of Kz-oil / insecticide combinations showed different levels of synergistic, additive and antagonistic effects. A high level of synergism was observed in Kz-oil / Aphox followed by Kz-oil / Sumicidin, Kz-oil / Sumithion, Kz-oil / Malathion, Kz-oil / Karate, Kz-oil / Neemix and Kz-oil / Selecron. The natural product, Neemix produced high toxic action when was combined with Reldan or Aphox, but it caused a slight synergism with Cyanox, Actellic or Selecron. As for the carbamate Aphox / insecticide mixtures, moderately synergistic effects were indicated with Aphox / MTI-446, Aphox / Tokuthion and Aphox / Sumicidin. Within pyrethroid / pyrethroid mixtures, Meothrin / Sumicidin and Meothrin / Karate produced moderate synergism. Within OP / OP insecticide mixtures, these mixtures caused different levels of additive or antagonistic effects except with Malathion / Actellic which produced synergistic effect.