INTRODUCTION: The hierarchy of stromal progenitors from the bone marrow is poorly characterized; multipotent mesenchymal stromal cells and colony-forming units of fibroblasts are isolated in culture. Mesenchymal stem cells do not have a unique combination of surface antigens, making it difficult to obtain the pure population. The expression of the nestin gene is often used as a marker of these cells. AIM: to evaluate the level of expression of the nestin gene in multipotent mesenchymal stromal cells and in colony-forming units of fibroblasts and to characterize the change in its expression during the transition from oligopotent progenitor cells to monopotent ones. MATERIALS AND METHODS: Stromal progenitors were analyzed in bone marrow samples from 19 donors by standard methods. A total of 296 individual clones of fibroblast colony-forming units were obtained from the same bone marrow samples. The cells were analyzed for the ability to differentiate toward the adipogenic and osteogenic lineages. Relative expression level of nestin gene was analyzed in all cells. RESULTS: Mean relative expression level of nestin did not differ significantly in multipotent mesenchymal stromal cells (0.410.13) and in the total population of colony-forming units of fibroblasts (0.240.05). In individual clones of colony-forming units of fibroblasts, nestin expression was not significantly higher than in the total population (0.310.04). When analyzing colony-forming units of fibroblasts differing in their differentiation potential, the highest expression of nestin was found in the group of monopotent osteogenic progenitors, while its expression was significantly lower in oligopotent progenitors. CONCLUSION: Nestin gene expression in mesenchymal stromal progenitors from the bone marrow is not specific for mesenchymal stem cells and cannot be used as a unique marker of this cell type. According to our data, a high level of nestin expression rather identifies monopotent osteogenic progenitors.