In patients referred for allogeneic hematopoietic stem cell transplantation (HSCT), iron overload is frequent and associated with increased morbidity and mortality. Both the evolution of iron overload after transplantation and its correlation with late posttransplantation events are unknown. We studied 290 patients undergoing myeloablative allogeneic HSCT between 2000 and 2009. Serum ferritin, transferrin saturation, transferrin, iron, and soluble transferrin receptor were determined regularly between 1 and 60 months after HSCT, and values were correlated with transplantation outcome. Ferritin levels peaked in the first 3 months posttransplantation and then decreased to normal values at 5 years. Transferrin saturation and iron behaved analogously, whereas transferrin and soluble transferrin receptor increased after an early nadir. Landmark survival analysis showed that hyperferritinemia had a detrimental effect on survival in all periods analyzed (0 to 6 months P < .001; 6 to 12 months P < .001; 1 to 2 years P = .02; 2 to 5 years P = .002). This effect was independent of red blood cell transfusion dependency and graft-versus-host disease. Similar trends were seen for other iron parameters. These data show the natural dynamics of iron parameters in the setting of allogeneic HSCT and provide evidence for a prognostic role of iron overload extending beyond the immediate posttransplantation period. Interventions to reduce excessive body iron might therefore be beneficial both before and after HSCT.