In this issue of Kidney International, the Dialysis Outcomes and Practice Patterns Study reports that hemodialysis patients with monthly intravenous iron supplementation of 300-399 mg or ⩾400 mg had a 13 or 18% higher risk of dying, respectively, compared with those receiving 100-199 mg per month, with no obvious differences in cause-specific mortalities. This study supports that randomized controlled trials are urgently needed to identify optimized iron supplementation strategies for anemic dialysis patients.