Background: It is still controversial that the stem cells isolated from human dental pulp meets the criteria for mesenchymal stem cells (MSCs). The aim of the present study was to examine whether or not they are MSCs, or are distinct stem cells population residing in tooth pulp. Methods: Adherent fibroblastic cells in the culture of pulp tissue from human third molars were propagated through several successive subcultures. Passaged-3 cells with a tendency to differentiate into odontoblastic cells were used to examine the key properties of MSCs including typical tripotent differentiation potential into bone, cartilage and adipose cell lineages and the expression of typical surface antigens. Moreover, they were examined for growth capacity in culture. Results: Dental pulp stem cells successfully progressed towards differentiation among three skeletal cell lineages. More than 90% of the cell population exhibited the expression of surface antigens known to be found on mesenchymal lineages such as CD105, CD90, CD44, and CD73, while only less than 2% expressed endothelial-hematopoietic epitopes including CD56, CD11b, CD34, CD31, CD33, and CD45. The cells exhibited a relatively high proliferation capacity with population doubling time of about 21.9 hours. Conclusion: The dental pulp stem cells are of MSC population, and may be considered suitable for use in regenerative medicine, owing to their relatively rapid rate of in vitro propagation.