The study was conducted to determine the' effect of dosing diets with pirimiphos-methyl on the performance and carcass yield of broilers. After a week of group brooding, 280 day-old Cobb broiler chicks were randomized into four treatments (0, 7, 8, 9 ppm pirimiphos-methyl) with seven replications following a completely randomized design. The insecticide, in the form of emulsifiable concentrate, was directly added into the mixed ration. Results showed that the live weight and live weight gain of broilers were significantly reduced by 13% and 14%, respectively when fed diets dosed with pirimiphos-methyl. Likewise, the treated groups showed significant incidence of leg paralysis compared with the control group. Feed consumption, feed efficiency and mortality rate were not significantly affected. Dressing percentages, with or without giblets, were significantly reduced using 9 ppm pirimiphos-methyl. An average of 21% reduction in income over feed and chick cost using the insecticide was also noted. This study showed that dosing diets with pirimiphos-methyl adversely affected the growth performance, carcass yield, and economics of raising broilers up to 38 days of age.