Cytosolic sulfotransferases (SULT) are involved in detoxification pathways. A functional polymorphism in the SULT1A1 gene, leading to an Arg213His substitution (SULT1A1*2), is thought to confer susceptibility to various types of cancer. Upper urinary tract urothelial cell carcinomas (UUT-UCC) are rare (5% of all urothelial carcinomas). We genotyped 268 patients with UUT-UCC and 268 healthy controls matched for age, gender, tobacco consumption, and ethnicity. His213 (SULT1A1*2) allele frequency was significantly higher in patients than in controls (37.1% versus 28.9%; P=0.004). The His/His genotype corresponding to low-activity SULT1A1 enzyme conferred a significantly higher risk of UUT-UCC (odds ratio, 2.18; 95% confidence interval, 1.28-3.69; P=0.004