Malathion is a non-systemic organophosphorous insecticide and acaricide with contact, stomach and respiratory action. The main use is in the agricultural sector. Acting through inhibition of cholinesterase enzymes, it is used to control a wide range of sucking and chewing pests including Hemiptera, Thysanoptera, Coleoptera, Diptera and Lepidoptera in a variety of field-crops and fruits. Other agricultural uses are protection of stored grain and grasshopper and locust control.

Large-scale application programmes include boll weevil eradication in the USA where Fyfanon® is the preferred insecticide. The boll weevil eradication programme has been in operation since 1987.

In public health programmes, malathion is used extensively to control major arthropod disease vectors, most importantly malaria and dengue fever transmitting mosquitoes. Malathion is one of the least acute toxic OP insecticides.