The use of bone marrow mononuclear cells (BMMNCs) as a source of mesenchymal stem cells (MSCs) for therapy has recently attracted the attention of researchers because BMMNCs can be easily obtained and do not require in vitro expansion before their use. This study was designed to quantify the MSC population in bone marrow (BM) samples obtained for cell therapy using flow cytometry to detect the CD271 antigen.Autologous BM was obtained by posterior superior iliac crest aspiration under topical anesthesia. Mononuclear cells isolated from the BM aspirate on a Ficoll density gradient were used to treat patients with pressure ulcer (n = 13) bone nonunions (n = 3) or diabetic foot ulcers (n = 5).Our flow cytometry data revealed a low percentage as well as a high variability among patients of CD271(+)CD45(-) cells (range, 0.0017 to 0.0201%). All cultured MSC adhered to plastic dishes showing a capacity to differentiate into adipogenic and osteogenic lineages.Our findings suggested that the success of cell therapy was independent of the number of MSCs present in the BM aspirate used for autologous cell therapy.