Basic fibroblast growth factor (bFGF) was shown to enhance rat stromal bone marrow cells in culture to produce mineralized bone-like tissue in response to dexamethasone (Dex) treatment (Pitaru et al., J Bone Miner Res 8:919; 1993). The purpose of this study was to explore the effect of bFGF on Dex-treated human stromal bone marrow cells (hSBMC) in culture. Human SBMC from 6 patients were cultured for 14 days (P₀) and then subcultured and grown for 28 days in the presence of Dex (10⁻⁸ mol/L). The effect of bFGF on cell proliferation at P₀ and protein content, DNA content, alkaline phosphatase activity (ALP), osteocalcin secretion, and formation of mineralized bone-like tissue (MBT) at P₁ was analyzed. bFGF treatment resulted in a 2.4-fold increase in cell number at P₀ and a concentration-dependent increase in [³H]-thymidine incorporation at P₁, reaching a maximum increase of 3.7-fold at a concentration of 0.3 ng/mL. Furthermore, bFGF significantly increased both DNA content (two- to threefold), protein content (five- to sixfold), and the amount of MBT (up to 20-fold) at P₁ cultures. Morphological evaluation of the MBT at the electron microscope level revealed a mineralization process along collagen fibrils similar to the natural process. The osteogenic nature of the bFGF-treated cultures was further shown by their ALP activity, as well as osteocalcin secretion in response to 1,25-dihydroxyvitamin D₃. In conclusion, bFGF demonstrated a stimulatory effect on the proliferation of Dex-treated hSBMC-derived osteoprogenitors while maintaining their capacity to fully differentiate and form bone-like tissue in culture.