Objective: To investigate the effects of the different doses of vitamin C on urinary albumin excretion rate （UAER）in diabetic rats. Methods: The rats were randomly divided into following groups: group C

control group; group D

streptozotocin-induced diabetic rats; group DT1

diabetic rats treated with vitamin C 30 mg/kg/d ; group DT2

diabetic rats treated with vitamin C 90; and group DT

diabetic rats treated with vitamin C 270 mg/kg/d. UAER were measured at 1

2

4

6 and 8 weeks

respectively. The concentrations of vitamin C in plasma and kidney were determined at 9 week. Results: Compared with group C

the levels of vitamin C in the plasma and kidney of group D decreased significantly（Ｐ<0.05）

which could be normalized by supplementation with vitamin C in group DT1

DT2 and DT3. At 4

6 and 8 weeks

levels of UAER in the group DT1

DT2 and DT3 had markedly decreared compared with group D（Ｐ<0.05），and there were no significant difference among DT1

DT2 and DT3

respectively. Conclusion: UAER decreased significantly in diabetic rats that received vitamin C. Administration of vitamin C in diabetic patients may be beneficial in attenuating the progression of diabetic nephropathy.