This study was undertaken to find effects of ethanol extracts from Bombyx mori on the hyperglycemia induced by streptozotocin in rats. Blood glucose level of rats increased depending on experimental days after streptozotocin treatment. But there was no difference in blood glucose level between the rats injected with ethanol extracts of B. mori and normal rats. There was no significant difference in the kidney fibrosis between the rats injected with ethanol extrscts of B. mori and normal rats at all ages examined. The transforming growth factor-$eta$l ($TGF-{eta}1$) protein was detected in the glomerulay endothelial cells and tubular epithelial cells of streptozotocin rats at 14 days of age. In the rats injected with ethanol extracts of B. mori to the kidneys, the $TGF-{eta}1$ protein was detected very faintly. The $TGF-{eta}1$ mRNA of streptozotocin rats increased at 14 days of age, and this was higher than the rats injected with ethanol extrscts of B. mori. Taken these together, the results suggest that the ethanol extracts of B. mori ameliorate hyperglycemia of the rats induced by streptozotocin.