Background: Deferasirox (DFX) is an effective and well-tolerated oral iron chelator elevating the adherence to iron chelating therapy among patients with iron overload. However, the US Food and Drug Administration issued a warning about the potential adverse events associated with DFX in 2010. Methods: To examine the risks of gastrointestinal (GI) bleeding, acute liver necrosis, and acute renal failure among DFX users compared with desferrioxamine (DFO) users in a real-world setting, first-time users of DFX or DFO between 2005 and 2008 in Taiwan's National Health Insurance database were observed in this population-based retrospective cohort study. The risks of different adverse events were individually analyzed by Cox proportional hazards models and adjusted by age, sex, concomitant medications, and prior medical conditions. Results: Deferasirox users had the highest incidence rates of GI bleeding (2.03 per 10000 patient-days), acute liver necrosis (0.26 per 10000 patient-days) and acute renal failure (1.45 per 10000 patient-days) compared with other iron chelator users. Compared with DFO users, DFX users were not associated with the risk of GI bleeding (adjusted HR 1.03, 95% CI 0.61-1.74, p=0.90) and the risk of acute liver necrosis (adjusted HR 2.13, 95% CI 0.49-9.33, p=0.32). The association between DFX use and acute renal failure was found to be statistically significant (HR 2.18, 95% CI 1.18-4.02, p=0.01; adjusted HR 2.41, 95% CI 1.27-4.58, p=0.01). Conclusion: In this study, we found statistically significant higher risk of acute renal failure and non-statistically significant higher risk of GI bleeding and acute liver necrosis associated with DFX use. More researches are warranted to evaluate the association between DFX use and potential adverse events.