Key Points• DFX-DFO combination followed by DFX monotherapy led to a meaningful decrease in myocardial and liver iron in severe siderosis patients.• Substantial liver iron reduction may be helpful in patients needing rapid control of liver iron (eg, pretransplant or planned pregnancy). Geometric mean mT2* ratios (Gmean month12/24 /Gmean baseline ) were 1.09 and 1.30, respectively, increasing from 7.2 ms at baseline (n 5 60) to 7.7 ms at 12 (n 5 52) and 9.5 ms at 24 months (n 5 36). Patients (17 of 60; 28.3%) achieved mT2* ‡10 ms and ‡10% increase from baseline at month 24; 15 switched to monotherapy during the study based on favorable mT2*. LIC decreased substantially from a baseline of 33.4 to 12.8 mg Fe/g dry weight at month 24 (252%). LVEF remained stable with no new arrhythmias/cardiac failure. Five patients discontinued with mT2* <5 ms and 1 died (suspected central nervous system infection). Safety was consistent with established monotherapies. Results show clinically meaningful improvements in mT2* in about one-third of patients remaining on treatment at month 24, alongside rapid decreases in LIC in this heavily iron-overloaded, difficult-to-treat population. Combination therapy may be useful when rapid LIC reduction is required, regardless of myocardial iron overload. This trial was registered at www.clinicaltrials.gov as #NCT01254227. (Blood. 2015;125(25):3868-3877)