Background: The incidence of acute kidney injury (AKI), the new term for acute renal failure, has increased in recent
years. Ischemia–reperfusion (IR) is one of the main causes of AKI. Erythropoietin (EPO) is a complex molecule, which
regulates red blood cell production in the bone marrow. Recent studies provide evidence of potential therapeutic effect of
EPO on AKI. Aim of the Work: Investigate the role of EPO in mobilization of bone marrow derived stem cells and its role in repairing AKI. Materials and Methods: This study included 32 adult male albino rats, divided into three groups; control, non-treated IR and EPO treated group. AKI was done by induction of IR via clamping both renal pedicles for 40 minutes and EPO 5000 U|kg was injected in treated group once intraperitoneally immediately after IR. Rats were sacrificed 48 hours and 1 week after intervention, then renal sections were stained with hematoxylin & eosin, PAS and immunohistochemically for CD34. Results: Erythropoietin improved the impaired kidney manifestations occurred by IR including increasing the reduced urea and creatinine levels, improved histological architecture of kidney. Also, increasing CD34 immunopositive hematopoietic and endothelial progenitor stem cells. Conclusion: This work concluded that administration of EPO at time of renal IR resulted in enhanced mobilization of stem cells resulting in structural recovery and improved functions.