Additionally, we found that the risk of bladder cancer associated with NQO1 Pro187Ser polymorphism was pronounced and statistically significant among never smokers (homozygous model: OR = 2.30, 95% CI = 1.14–4.65; heterozygous model: OR = 2.26, 95% CI = 1.43–3.56; dominant model: OR = 1.59, 95% CI = 1.14–2.21, and allele comparing: OR = 1.72, 95% CI = 1.27–2.33), but no association was detected when smokers were considered. The gene discussed is NQO1; the disease is urinary bladder cancer.