This study is aimed to design a chemically-defined serum free medium (CDSFM) to support in vitro culture of bone marrow-derived mesenchymal stem cells (BM-MSCs). BM-MSCs were isolated from the femoral bones of one-month-old New Zealand Rabbits with density gradient centrifugation. We compared the proliferation capability, cell cycle, colony-forming efficiency, osteogenic and adipogenic differentiation capabilities of BM-MSCs cultured in CDSFM with those cultured in serum-containing medium (SCM). After 10 days culture, BM-MSCs were expanded by 50 folds in CDSFM, while only 40 folds in SCM. EGF, bFGF and hy-drocortisone were the most important additives and significantly stimulated BM-MSCs proliferation. The percentage of cells at G0-G1 cell cycle was 80.31% +/- 0.58% after CDSFM culture, with no significant difference (P>0.05) compared to 75.24% +/- 4.05% for SCM culture. However, the cloning efficiency of BM-MSCs cultured in CDSFM was significantly lower than that in SCM (P<0.01). The expanded BM-MSCs in CDSFM preserved differentiation potentials into mesenchymal lineages in vitro, including adipocytes and osteoblasts. We have designed a chemically-defined serum free medium that could support in vitro proliferation and maintain the properties of BM-MSCs as stem cells, which could be applied to cell-based therapy and biomedical research.