Two commercial bioinsecticides; Protecto (Bacillus thuringiensis var. kurstaki) and Viruset (Spodoptera littoralis/NPV) were bioassayed against the cotton leaf worm (CLW), Spodoptera littoralis (Boisd.) (2^nd and 4^th instar larvae). The obtained results reveal that Protecto was the most potent bioinsecticide compared with Viruset. Treatment of 2^nd and 4^th instar larvae with LC₅₀'s of Protecto and Viruset affected estimated biological aspects. The larval, pupal, and adult longevity durations were prolonged due to treatment. It was also observed that egg number and hatchability were affected by treatment.