This study aimed to investigate the combined effect of lufenuron and gamma radiation against the cotton leaf worm. Full-grown pupae were irradiated with a substerilizing dose 100Gy, and the 4th instar larvae of the F₁ were used in the experiments. The results revealed that the percent mortality was time- and concentration-dependent, and the F₁ larvae were more susceptible to lufenuron than the normal larvae. The enzymatic analysis of phenoloxidase and acetylcholinesterase activities showed that the F₁ larvae treated with LC₅₀ of lufenuron exhibited the highest activity when compared to larvae treated with LC₅₀ of lufenuron or F₁ larvae. We conclude that a combination of gamma radiation and lufenuron could be an excellent integrated control program for Spodoptera littoralis.