BACKGROUND Whole blood donors are at risk of becoming iron deficient. To monitor iron stores, Sanquin implemented a new deferral policy based on ferritin levels, in addition to the traditional hemoglobin measurements. METHODS Ferritin levels are determined in every fifth donation, as well as in all first‐time donors. Donors with ferritin levels <15 ng/mL (WHO threshold) are deferred for 12 months; those ≥15 and ≤30 ng/mL for 6 months. The first results were analyzed and are presented here. RESULTS The results show that 25% of women (N = 20151, 95% CI 24%‐25%) and 1.6% of men (N = 10391, 95% CI 1.4%‐1.8%) have ferritin levels ≤30 ng/mL at their first blood center visit. For repeat (non‐first‐time) donors, these proportions are higher: 53% of women (N = 28329, 95% CI 52%‐54%) and 42% of men (N = 31089, 95% CI 41%‐43%). After a 6‐month deferral, in 88% of returning women (N = 3059, 95% CI 87%‐89%) and 99% of returning men (N = 3736, 95% CI 98%‐99%) ferritin levels were ≥15 ng/mL. After a 12‐month deferral, in 74% of returning women (N = 486, 95% CI 70%‐78%) and 95% of returning men (N = 479, 95% CI 94%‐97%) ferritin levels increased to ≥15 ng/mL. CONCLUSION Deferral of donors whose pre‐donation ferritin levels were ≤30 ng/mL might prevent donors from returning with ferritin levels <15 ng/mL. This policy is promising to mitigate effects of repeated donations on iron stores.