The effect of various microbial pesticides and its binary mixtures against 2^nd instar larvae of cotton leafworm Spodoptera littoralis (Boisd), were studied. Results of laboratory experiments revealed that lc₅₀ and toxicity index of the tested compounds against 2^nd instar larvae of cotton leafworm were (0.52, 4.81, 147.003, 180.30, 205.30, 205.35, 249.9 and 1065.90 PPM.) for Spinetoram, Spinosad, Abamectin, Diple DF, Agerin, Protecto and Viroset respectively. The toxicity index were (100, 10.81, 0.35, 0.29, 0.25, 0.21 and 0.05 %) for mentioned obvious tested compounds respectively.                 Co-toxicity factors of the binary mixture of (Spinetoram+ Diple DF), (Spinetoram + Agerin), (Spinosad + Diple DF), (Spinosad + Agerin), (Abamectin +Diple DF) and (Abamectin + Agerin) and LC25 levels against 2^nd instar larvae of cotton leaf worm S.littoralis were (-30 and – 49.46), (+ 528.5, + 30) and (+ 657.14 and + 390), respectively.