Three varieties of commonly used mulberry leaves (V1, Local, S1635) were fed to the Bombyx mori larvae [Bivoltine double hybrid – (AP71 x AP9)(AP72 x AP8)] and their influence on the larval weight, filament length and larval protein content was studied under natural conditions in Mizoram. The mean weight of larvae, pupae, cocoon and shell as well as cocoon shell ratio and larval protein content of B. mori were increased when fed with S1635. In addition, the filament length produced by this silkworm in response to S1635 showed significant increase with respect to the other two varieties. Positive correlation was observed in filament length against protein content. The overall performance of B. mori in terms of growth and economic parameters was significantly improved with S1635 and this variety has the potential to enhance the commercial qualities of silk. Therefore, it is suggested to be used in sericulture for higher yield of silk.