Objective: Multipotent mesenchymal stromal cells (MSCs), previously known as “mesenchymal stem cells”, are a group of multipotent and clonogenic cells. These cells were primarily found among the bone marrow (BM) stroma. A new marker called “mesenchymal stem cell antigen 1 (MSCA1)” has been found among BM-MSCs which is thought to be specifically expressed on MSCs. The Goal of this study was to assess presence of this newly found MSCs antigen on the mononuclear cells from other sources. Materials and Methods: Five samples of BM and Granulocyte colony stimulating factor mobilized peripheral blood (G-CSF mobilized-PB) from the remnant part of bags used for bone marrow transplantation were collected. Mononuclear cells (MNCs) were isolated on the Ficoll layer and underwent flowcytometry for CD73, CD34, CD45, CD14, CD90, CD44, CD166, HLA-DR, CD271 and MSCA1. Results: Among BM-MNCs 0.22 percent of cells were positive for MSCA1. Ninety percent of these cells were positive for CD271 and negative for CD45. The percent of MSCA1 positive cells in G-CSF mobilized-PB was raised up to 2.54 but 68% of these cells were positive for CD45 Conclusion: It has been shown that MSCs are a heterogeneous population and in some reports they do express CD271 and MSCA1 less than 60% also these two markers have been used widely for purification and enrichment of MSCs. Regarding our data MSCA1 in GCSF mobilized-PB specifies cells from hematopoietic origin other than mesenchymal stem cells. MSCA1 is a good marker for isolation of MSCs from BM but not from other sources.