Recently, a functional insertion/deletion polymorphism (-94 insertion/deletion ATTG) in the promoter of NFKB1 gene, which encodes the p50 subunit of nuclear factor-kappaB protein complex, was identified. The aim of this study was to explore the association between this polymorphism and bladder cancer in a Chinese population. The NFKB1 polymorphism was assessed in 207 patients with superficial transitional cell carcinomas in bladder and in 228 age-, sex-, and smoking-matched healthy volunteers. The polymerase chain reaction assay was used to determine the NFKB1 genotypes. Genomic DNA used for the assay was extracted from peripheral blood lymphocytes. This study found that the frequency of ATTG(2) allele in bladder cancer patients was significantly higher than that in control subjects (65.2% vs. 56.1%, p = 0.006, odds ratio = 1.465), suggesting that the functional NFKB1 promoter polymorphism is associated with increased risk for superficial transitional cell carcinoma of the bladder.