The p53 tumor suppressor gene is often mutated in various human cancers. Recently, the p53 codon 72 polymorphism has been extensively studied to determine the risk factors responsible for cancer formation. We investigated the genotype distribution of the p53 codon 72 polymorphism in 112 male urothelial cancer cases and 175 male unrelated non-cancer controls. The allelic frequencies in Japanese non-cancer controls were 0.58 (Arg) and 0.42 (Pro). There was no significant difference in the three genotype frequencies (Arg/Arg, Arg/Pro, Pro/Pro) of the p53 codon 72 between the urothelial cancer cases and the controls. However, stratifying by smoking status, we found that the frequency of the Pro/Pro genotype for smokers was significantly more than that for never-smokers (odds ratio (OR)=2.28, 95% confidence interval (95%CI)=1.12-4.66). Furthermore, we divided smoking status (pack-years) into quartiles (<20, 20-40, 40-60, >60). OR (Pro/Pro vs. Arg/Arg) for the lighter smokers (<20 pack-years) was higher than in other groups (OR=6.83). Our results suggest that the Pro/Pro genotype of the p53 codon 72 polymorphism increases the risk of urothelial cancer in smokers.