Several studies have investigated the associations between X-ray repair cross-complementing group 3 (XRCC3) Thr241Met polymorphism and the susceptibility to lung cancer and bladder cancer, but results have been inconclusive. In order to derive a more precise estimation of the relationship, a meta-analysis was performed. A total of 22 case control studies, including 2976 cases and 4495 controls for lung cancer, and 3445 cases and 4599 controls for bladder cancer, met the inclusion criteria and were selected. Overall, there was no evidence showing a significant association between XRCC3 Thr241Met polymorphism and lung cancer risk. Furthermore, the results for bladder cancer showed that significant decreased risk was found for the additive model (odds ratio [OR] = 0.959, 95% confidence interval [CI], 0.924-0.996) and dominant model (OR = 0.982, 95% CI, 0.963-1.000) but not for the recessive model (OR = 0.958, 95% CI, 0.905-1.014). In summary, our meta-analysis indicates that XRCC3 Thr241Met polymorphism may be weakly associated with the risk of bladder cancer. (Cancer Sci 2010).