Background: The clinical use of G-CSF has recently been expanded to include mobilization of stem cells for both autologous and allogeneic transplantation. Most of the published studies have focused on stem cells released into the peripheral blood (PB) after G-CSF treatment. However, little is known about the effect of G-CSF on BM. This study evaluated the concurrent effects of short-term G-CSF on both BM and PB stem and progenitor cells in normal individuals. Methods: Volunteers received 5 or 10 μg/kg of G-CSF for 5 consecutive days (Days 1-5). On Days 0, 3, 6, 9 and 15, BM and PB samples were obtained. Flow cytometry and functional assay were performed to analyze stem cells, subpopulations, adhesion molecules, colony-forming units and LTCIC. Results: The total nucleated cells and absolute numbers of CD34+/mL showed a similar response pattern in both BM and PB, with a peak around Day 6 that returned to baseline levels by Day 15. However, there was a reciprocal change in the percentage of CD34+ cells between BM and PB compartments. The expressions of adhesion molecule showed an up- and down-regulation of α4 and α5 integrin subunits, respectively, also correlated with the CD34+ mobilization patterns. Discussions: The functional characterization of integrins, and further clinical examination of G-CSF-stimulated BM is warranted. G-CSF-stimulated BM may be considered as an alternative source of stem cells in transplantation.