Objectives To evaluate the long-term efficacy and safety of deferasirox therapy in a large observational cohort of children with transfusion-dependent thalassemia (TDT) and sickle cell anemia (SCA) in Turkey. Methods This was a multicenter, prospective cohort study including TDT and SCA patients aged 2-18 years with iron overload (>= 100 mL/kg of pRBC or a serum ferritin [SF] level >1000 mu g/L) receiving deferasirox. Patients were followed for up to 3 years according to standard practice. Results A total of 439 patients were evaluated (415 [94.5%] TDT, 143 [32.6%] between 2 and 6 years). Serum ferritin levels consistently and significantly decreased across 3 years of deferasirox therapy from a median of 1775.5 to 1250.5 mu g/L (P < 0.001). Serum ferritin decreases were noted in TDT (1804.9 to 1241 mu g/L), SCA (1655.5 to 1260 mu g/L), and across age groups of 2-6 years (1971.5 to 1499 mu g/L), 7-12 years (1688.5 to 1159.8 mu g/L), and 13-18 years (1496.5 to 1107 mu g/L). Serum ferritin decreases were also noted for all deferasirox dose groups but only significant in patients with doses >= 30 mg/kg/d (n = 120, -579.6 median reduction, P < 0.001). Only 9 (2%) patients had adverse events suspected to be related to deferasirox. Serum creatinine slightly increased but remained within the normal range. Conclusions Deferasirox has long-term efficacy and safety in children with TDT and SCA, although higher doses (>= 30 mg/kg/d) may be required to achieve iron balance.