Abstract： Objective To investigate the effects of Tangmaikang on oxidative and carbonyl stress in streptozocin-induced diabetic rat kidneys,and to also explore their reno- protecting mechanisms in diabetic rats.Methods Rats were randomly divided into three sub-groups:normal control (group A),diabetic control (group B) and diabetic with Tangmaikang (group C).Blood glucose,blood lipid,HbAlC,kidney to body weight ratio and urinary protein excretion were measured after 12 weeks.Malonyldialdehyde (MDA)level,superoxide dismutase (SOD) activity,glutathione peroxidase (GSH-Px) activity,total sulfhydryl group and protein carbonyl levels in renal tissue were also determined.Results Compared to group A,kidney to body weight ratio,urinary protein excretion,MDA,and protein carbonyl levels in group B were significantly higher,while SOD and GSH-Px activities and total sulfhydryl group level were significantly lower than those in group A.Kidney to body weight ratio,urinary protein excretion,MDA,and protein carbonyl level in group C were significantly lower than those in group B.SOD and GSH-Px activity in group C were higher than those in group B.Conclusion Tangmaikang can prevent renal hypertrophy and decrease urinary protein excretion in diabetic rats.The renoprotective effects of this drug may be related to his ability to inhibit oxidative and carbonyl stress.