Abstract: Bone marrow derived-Human Mesenchymal stem cells (hMSCs) are non-hematopoetic, stromal cells that demonstrate multilineage differentiation capacity and being capable to give rise to diverse tissues, including bone and cartilage. Due to this capability, hMSCs are currently evaluated for regenerative medicine, repopulating injured tissues and clinically ablated diseased tissues with healthy, terminally differentiated cells. Thus, for therapeutic applications, enough numbers of homogenous MSCs are required. In this study, the population doubling of bone marrow derived hMSCs was assessed in early and late passages. It was noted that in healthy cells, generally, the population doubling increases over time due to the slower rate of cell growth. Subsequently, the mesengenic multipotency of BM-MSCs for chondrogenesis, osteogenesis and adipogenesis was investigated in early and late doublings. According to our findings, the early passage hMSCs treated with the differentiation agents exhibited approximately 100, 48±10.33 and 28.6±6.62% osteocytes, chondrocytes and adipocytes, respectively. Whereas, the late passage hMSCs subjected to the differentiation agents only demonstrated the high degree of osteogenicity but they revealed neither chondrogenicity nor adipogenicity. Furthermore, the Expression of Oct4, Sox2 and Nanog genes in undifferentiated human BM-derived MSCs was studied. The result revealed the Oct4 is expressed at very low levels in early passage MSCs and disappeared at late passage however Nanog and Sox2 were almost undetected in MSCs. In conclusion, the proliferation rates and other properties of the cells gradually change during expansion and therefore, it is recommended to not expand hMSCs beyond four or five passages.