Background: Aging is a complex natural process including every molecule, cell and organ in the body. In its broadest mean, aging refers to changes that occur during the life span. Some of these changes are not harmful while other increase the risk of diseases.   Aim: The purpose of the current study was to investigate the histological and immunohisto- chemical effects of bone marrow derived stem cells on age changes of pulp in albino rats.   Material and methods: Forty five (fifteen adults aging six months and thirty olds aging fifteen months) male albino rats were divided into three equal groups. Group I (Adult group) that get infused with saline intravenously to serve as control group, group II (old age group)  which also get  infused with saline intravenously and group III (old age injected by stem cells). The source of stem cells was from additional fifteen albino rats six weeks old which will be used for isolation and culture of bone marrow stem cells.   Results: Old age group revealed sever histological alterations and negative Ki67 expression compared to control group while old group injected by stem cells revealed histological reorganizations of the pulp cells and mild to moderate Ki67 expression that was nearly similar to control group.   Conclusion: Intravenous injection of bone marrow mesenchymal stem cells improved the histological features of the pulp compared to old group and also it had a positive proliferating effect by the enhanced expression of Ki67