Human oxoguanine glycosylase 1 (hOGG1) is a DNA repair enzyme, which plays important roles in the base excision repair (BER) pathway. Several studies reported a common polymorphism Ser326Cys (rs1052133) in hOGG1, which conferred the susceptibility of bladder cancer. We hypothesized that the polymorphism is associated with risk of bladder cancer in a Chinese population. In a case-control study of 1050 histologically confirmed bladder cancer patients and 1404 age and sex matched healthy controls, we genotyped the hOGG1 Ser326Cys polymorphism using TaqMan technology and assessed its association with bladder cancer risk. We found that the hOGG1 Ser/Cys + Ser/Ser genotypes were associated with a significantly increased risk of bladder cancer (adjusted odds ratio [OR] = 1.19, 95% confidence interval [CI] = 1.01–1.41), compared with the Cys/Cys genotype. Furthermore, the increased risk was more pronounced among subjects over age 65 years (OR = 1.31, 95% CI = 1.04–1.66), male subjects (OR = 1.21, 95% CI = 1.00–1.47), ever smokers (OR = 1.29, 95% CI = 1.00–1.68) and heavy smokers (>20 pack-years) (OR = 1.45, 95% CI = 1.03–2.04). No significant association was observed in the stratification of tumor grade and tumor stage for bladder cancer. In conclusion, our results suggest that hOGG1 Ser326Cys polymorphism may contribute to the susceptibility to bladder cancer in a Chinese population. (Cancer Sci 2012; 103: 1215–1220)