Probiotics are viable, non-pathogenic microorganisms which when administered in adequate amounts, confer a health benefit on the host. Mulberry leaves supplemented with Saccharomyces cerevisiaen (yeast)andBifidobacterium bifidum (bacteria) probiotics were used to feed two silkworm hybrids. The impact of micro-organismsadministration was studied on larval, pupal and cocoon and shell weights. As well as, ERR, cocooning, pupation and cocoon shell percentages. Silk filament length, breaks and silk % were recorded. Digestive enzymes (Protease, Invertase and Amylase) were estimated colorimetricaly. The results revealed that, B. bifidum and S. cerevisiae improved most tested parameters comparing with control. The effect of probiotics may be dependent on the tested Bombyx mori hybrid. Renditta that stands for the quantity of cocoons required for producing a kilogram of raw silk was significantly improved in all supplemented groups either for B. bifidum or S.cerevisiae. The lowest cocoon kilograms required to produced one kilo of raw silk was (5.97±1.85) recorded for hybrid 2 treated with B. bifidum.There is a pronounced increase in the activity of protease, amylase and invertase in probiotic treated worms than control.