The present work was conducted to evaluate the ovicidal and larvicidal activity of three insect growth regulators, flufenoxuron, chlorfluazuron and lufenuron against the cotton leafworm Spodoptera littoralis (Boisd.). Data indicate the important role played by age of eggs in determining the ovicidal activity against cotton leafworm S. littoralis eggs. In general, data indicated the superior ovicidal activity of lufenuron on egg masses followed by flufenoxuron and chlorfluazuron according to the toxicity index. While the field recommended rate of the tested IGR's caused reduction in the percent of hatchability compared with check. Regarding the efficacy of tested IGR's on 2^nd and 4^th instars larvae of S. littoralis, data cleared that lufenuron proved to be the most effective tested IGR against 2^nd instar larvae of S. littoralis (Boisd.) followed by chlorfluazuron and flufenoxuron, respectively. In a different trend, flufenoxuron was the most effective followed by lufenuron and chlorfluazuron against 4^th instar larvae of S. littoralis. The general mean of cumulative mortality could be arranged in following order: lufenuron, chlorfluazuron and flufenoxuron against the 2^nd & 4^th instars larvae under field – laboratory condition. In field efficacy of tested IGR's in 2012 season, data showed that the initial effects of chlorfluazuron and lufenuron were most striking, which was causing 95.21 and 90.44% reduction, respectively. While the lowest obtained with flufenoxuron which caused 64.91% reduction in population density than control. At ninth day, no significant differences were obtained among all tested IGR's.