This study has been carried out to understand the effect of Rehmanniae Radix, Hovenia dulcis, and Trichosanthis Radix water extract on the hyperglycemic mice induced with streptozotocin (STZ). A 60 mg/kg of STZ injection was given to mice twice in 24 hour intervals and then a 120 mg/kg STZ injection was given three days after the earlier injections. The control group was subjected to natural recovery, however, the treated groups were fed 0.2 mL (PA group) or 0.4 mL (PB group) of several herbal medicine extracts daily for six weeks. The weight of the PA group was higher than that of the control, but the weight of the PB group was lower than that of the control. The blood glucose level of the control group increased continuously, reaching to 350 mg/dL after six weeks, however, the PA and PB groups decreased compared with the control group. The creatinine levels are were significantly (p<0.01) decreased in the PA group compared with the control group. The BUN levels were decreased in the experimental groups compared with the control group. According to the histophatological observation of the control group, the basement membrane of the endothelial cells and podocytes in the glomeruli were thickened, but not observed in the experimental groups. Our study indicates that herbal water extract protects against diabetic kidney disease through multiple mechanisms, including ameliolating glomeruli injury, and lowering BUN and creatinine contents.