Two-week PR65 treatment of iron-loaded hepcidin knockout mice caused modest redistribution of iron. Hepcidin knockout mice were kept on a 300 ppm iron diet for their entire lifespan. Starting at 12 weeks of age, one group of mice was injected subcutaneously with solvent (n = 4) and the other with 50 nmol of PR65 (n = 4) daily for 2 weeks. Iron and hematologic parameters were measured 24 hours after the last injection. In PR65-treated mice compared with solvent-treated mice: (A) spleen iron increased more than 15-fold confirming PR65 activity; (B) serum iron concentrations were similar 24 hours after the last injection; (C) hemoglobin decreased by 2 g/dL indicating iron restriction to erythropoiesis; (D) heart iron tended to decrease, though the difference was not statistically significant at the number of mice tested; and (E) liver iron decreased by approximately 20%.