The novel findings of the present study are; 1) indoxyl sulfate downregulated expression of Nrf2 in proximal tubular cells, which was alleviated by an inhibitor of NF-κB and siRNA specific to NF-κB p65, 2) indoxyl sulfate downregulated expression of Nrf2, HO-1 and NQO1 and increased expression of 8-OHdG in rat kidneys, and 3) AST-120 which reduced serum indoxyl sulfate, upregulated expression of Nrf2, HO-1, and NQO1 and decreased expression of 8-OHdG in CKD rat kidneys. This evidence concerns the gene NQO1 and chronic kidney disease.