Acute radiation syndrome (ARS) is called as radiation sickness or radiation toxicity caused by abnormally high exposure to ionizing radiation in a very short period of time.¹  High doses of ionizing radiation are able to contribute to detrimental systemic effects in different organs.² In treatment of patients with ARS, physicians have used growth factors, cytokines and bone marrow transplantation.³ Mesenchymal stem cells (MSCs) have the potential for multilineage differentiation.^4,5 Bone marrow-derived stem cells (BMSCs) are the most well- known type of the mesenchymal stem cells used with safety and efficacy in several diseases such as ARS.¹ The present study assessed the regenerative effect of bone marrow-derived stem cells on cell count and survival in Acute Radiation Syndrome.