Field and laboratory trials were conducted in Zagazig – Sharkia Governorate during 2007 and 2008 cotton seasons to evaluate the efficacy of emamectin benzoate (against cotton leafworm Spodoptera littoralis and pink bollworm Pectinophora gossypiella. Emamectin benzoate resulted in initial kill of 93.73 and 92.39 % reductions in the numbers of cotton leafworm Spodoptera littoralis, larvae, comparing with 98.22 and 95.93 % for the recommended IGR hexaflumuron (Consult) (while as the residual effect emamectin benzoate revealed to 83.69 and 82.35% reductions comparing with 95.07 and 93.93 % for the hexaflumuron, in 2007 and 2008 cotton seasons, respectively. The efficiency of emamectin benzoate in comparison with the recommended insecticide chlorpyriphos (Dursban) against cotton bollworm, pink bollworm, Pectinophora gossypiella, they resulted in 59.40 and 54.68% for emamectin benzoate, and 81.81 and 83.21% for chlorpyriphos as average seasonal reductions, during the two cotton seasons, respectively. Laboratory trials revealed that LC50 and LC90 of emamectin benzoate were higher with cotton leafworm than pink bollworm, which were 2.783 and 1.656 ppm at LC50, while they were 29.096 and 11.193 ppm at LC90, respectively. The slope value of emamectin benzoate with cotton leafworm was 1.257 less than with pink bollworm which recorded 1.544.