The dietary proteins and amino acids are utmost important for the silkworm larvae due their active synthesis of silk protein in turn reflect on cocoon production. An attempt has been made in the current investigation to record the effect of mulberry leaves supplemented with methionine at varied concentrations viz., 0.5, 1.0 and 1.5% on the economic traits as well as aminotransferase enzymes in multivoltine silkworm breeds MU303 and MU11. The results of the study revealed that, both the breeds expressed notable improvement for economic traits which include larval weight, cocoon weight, shell weight, filament length, filament weight, renditta and fecundity at 0.5 % methionine supplementation when compared to other concentrations. Further, aspartate aminotransferase activity level was relatively high when compared to alanine aminotransferase in the fat body tissue of both the breeds at 0.5 % concentration. The enzyme activity levels was maximum in prior to spinning stage followed by fifth instar 3rd day and fifth instar 1st day.