Adult stem cells are remarkably plastic in their developmental potential when exposed to new mi- croenviroments or cultured in vitro.The primary roles of adult stem cells in a living organism are to maintain and repair tissue in which they are found.Bone marrow contains hematopoietie stem cells (HSCs),which dif- ferentiated into every type of mature blood cells;muhipotent adult progenitor ceils (MAPCs);and mesenchymal stem cells(MSCs),which can differentiate into mature cell of mutiple mesenchymal tissues including bone, cartilage and fat.They also have ability to differentiate into additional mature,nonhematopoietic cells of nerve, skeletal muscle,skin,myocytes of heart,liver,kidney and lung.The experimental progress of research about the plasticity of bone marrow stem cells in the last few years are reviewed.