Previous studies have shown that nonsteroidal anti-inflammatory drug (NSAID) use might be associated with a lower risk of developing cancer in the general population. Patients on dialysis have increased risk for cancer, but there are no studies to determine the relationship between NSAID use and cancer risk in these patients. To identify any association between NSAID use and cancer risk in patients with end-stage renal disease on dialysis, we used Taiwan's National Health Insurance database to conduct a nationwide population-based, propensity score-matched cohort study. All cancers between groups were compared by Cox proportional hazards models. Compared to nonuse of NSAIDs, the use of non-COX-2-selective inhibitors (hazard ratio 0.81, 95% confidence interval 0.67-0.97) or COX-2-selective inhibitors (0.78, 0.62-0.98) was associated with a lower risk of developing cancer. NSAID use reduced the risk of respiratory (0.39, 0.19-0.79), breast (0.41, 0.19-0.89), kidney (0.58, 0.38-0.88), digestive tract (0.64, 0.49-0.85), and bladder cancers (0.73, 0.55-0.96). NSAID use, however, significantly increased risk for upper gastrointestinal bleeding (odds ratio, 1.15, 1.07-1.23) but not adverse cardiac or cerebrovascular events. Thus, NSAID use was associated with a lower risk of developing cancer in chronic dialysis patients; however, they should still be used with caution due to the side effects of gastrointestinal bleeding.