OBJECTIVE: To investigate the effect of cadmium chloride on the expression of kidney injury molecule-1( KIM-1)in human renal tubular epithelial cells( HK-2 cells). METHODS: HK-2 cells at logarithmic phase were divided into a control group and 5 treatment groups that were treated with 5. 0,10. 0,20. 0,50. 0 and 100. 0 μmol / L of cadmium chloride dissolved in phosphate buffer solution. Cell pathology observation was carried out after 24 hours of cultivation. The methyl thiazolyl tetrazolium assay was used to calculate the survival rate of HK-2 cells. The expression of KIM-1 mRNA and protein were detected by the reverse transcription-polymerase chain reaction and Western blotting analysis respectively.RESULTS: There were no cellular morphologic change in HK-2 cells in the control group,the 5. 0 and 10. 0 μmol / L groups;the HK-2 cells showed different degree of swellings or vacuoles in the 20. 0 and 50. 0 μmol / L groups; a large number of cells were found dead in the 100. 0 μmol / L group. The cell survival rates of HK-2 cells in the 20. 0,50. 0 and 100. 0μmol /L groups were lower than those of control group,the 5. 0 and 10. 0 μmol /L groups( P < 0. 05). The pairwise comparison among survival rates of the 20. 0,50. 0 and 100. 0 μmol / L groups showed significant difference( P < 0. 05).The expression levels of KIM-1 mRNA and protein in the 20. 0 and 50. 0 μmol / L groups were higher than those of control group,the 5. 0 and 10. 0 μmol / L groups( P < 0. 05). The levels of KIM-1 mRNA and protein in the 50. 0 μmol / L group were higher than those of the 20. 0 μmol / L group( P < 0. 05). CONCLUSION: Cadmium chloride at certain concentration can increase the expression of KIM-1 mRNA and protein in HK-2 cells. Therefore,the expression of KIM-1 could be used as one of the effect biomarkers for cadmium induced kidney tubule injury.