Abstract: Objective To study toxic effects of cadmium(Cd)on the kidney,and discuss the mechanism of to xicity induced by Cd in kidney.Methods Three Cd groups rats were injected with CdCl₂ 3,5 and 7 μmol/kg per day for 6 weeks,respectively.Urinary Cd,protein contents and N-acetyl-B-D-glucosaminidase(NAG),alkaline phosphalase(ALP),lactic dehy drogenase(LDH)were measured.Malondialdehyde(MDA),glutathione(GSH)contents in the liver and renal cortex were determined.Results Urinary Cd,protein contents,NAG,A LP,LDH activities and MDA,GSH contents in the liver and renal cortex increased with Cd dose increasing.Urinary protein contents,NAG,LDH activities and MDA,GSH contents in the renal cortex of middle-dose Cd group were higher significantly than those of control and low-dose Cd group.To high-dose Cd group,ur inary protein contents,ALP activities and MDA contents in the liver and renal cortex were higher significantly than that of control,low-and middle-dose Cd group.Urinary Cd,protein contents and NAG,ALP,LDH activities were corr elated positively with MDA contents in the renal cortex.Conclusion The biological effect of Cd enhanced with Cd dose increasing.CdCl₂ 5μmol/(kg·bw)could induce renal injuries,and CdCl₂ 7μmol/(kg·bw)could induce more evident injuries.Furthermore,the mechanism was correlated positively with oxidative injuries caused by Cd.