In order to confirm and further examine the influence of genetic variations on the clinical outcome and toxicity of intravesical instillation agents, the aim of this study was to examine the GSTP1, GSTO1, GSTO2, and ABCB1 polymorphisms in a cohort of Chinese bladder cancer patients treated with epirubicin or MMC. The gene discussed is ABCB1; the disease is urinary bladder cancer.