The effect of feeding the silkworm Bombyx mori L. on six different mulberry variety Morus alba var. Kokuso-27, Sh2 x Lunlog, Kaeryang- ppong, Kanava-2, Leavigata, and Morus nigra var. Arandaly on some enzymatic activities which affect silk production was studied3-Phosphoglycerate Dehydrogenase (3-PGD, Glutamic Oxaloacetic Transaminase (GOT) and Glutamate Pyruvic Transaminase (GPT) which play a vital role in the synthesis of silk protein were determined. Results indicated that feeding silkworm larvae on Morus alba var. Kokuso-27 represented the highest rate of 3-PGD activity (6.14 u/mg) followed by Sh2xLunlog variety (5.76 u/mg) and Arandaly (4.2 u/mg) while, slight differences in 3-PGD activity was found between the other three varieties. The same with GPT enzyme, the mulberry varieties Morus alba var Kokuso-27 followed by Sh2xLunlong fed to larvae resulted in a high rate (5.21, 4.38 U/L), respectively. However, Kanava-2 recorded higher value of GOT followed by Leavigata (11.16 and 9.82U/L), respectively