The study was related to the chemical control of cabbage caterpillar (Pieris brassicae). The experiment was laid out in a complete randomized design (CRD) followed by five treatments with five replications to evaluate the efficacy of different insecticides against Pieris brassicae on cabbage, cauliflower and broccoli. The four synthetic insecticides ( Dimethoate 40% EC @ 400 ml /acre, Acetamiprid 20 SL @ 125 ml/acre, Profenophos 500 EC @ 400 ml/acre and Emamectin benzoate 5% EC) were used as treatment and a water as a control. The maximum percentage mortality was recorded in profenofos 77.5%,followed by emamectin benzoate 72.93%, dimethoate 72.63% and acetamiprid 58.93% respectively. So, these results showed that acetamiprid is less toxic to Pieris brassicae because it caused less mortality after 72 hours while profenophos is highly toxic because it caused 77.5 % mortality in 72 hours. While the remaining insecticides( Dimethoate 40% EC @ 400 ml /acre and Emamectin benzoate 5% EC)are less toxic than Profenofos against Pieris brassicae.