Background: Bladder cancer is a very common malignancy worldwide; its exact cause is not known, but it is believed to be multifactorial mostly caused by genetic mutations of tumor suppressor gene, proto-oncogenes and DNA repair genes including XRCC3 Thr241Met gene polymorphism. Aim of the study: Identify the link between XRCC3 (rs861539) gene polymorphism and the susceptibility to develop urothelial carcinoma of the bladder (UCB) in the Egyptian patients. Subjects and method: The presence of XRCC3 Thr241Met gene polymorphism (rs 861539) was identified by PCR-RFLP method in 50 patients with urothelial carcinoma of bladder and 50 healthy controls. Results: XRCC3 Thr 241 Met gene polymorphism CC genotype and C allele demonstrated a substantially increased susceptibility in the UCB group than the control group for the risk to develop UCB (OR 3.69, 95% CL 1.52-8.97) (P =0.003). However, while TT
genotype and T allele demonstrated a substantially decreased susceptibility in the UCB group than the control group with a

protective effect against UCB development (OR 0.096, 95%CL0.035-0.263) (P