Obsjective:To investigate the effects of differentaction time of IL-1β on the osteogenic capacity of bone marrow mensenchymal cells(BMMSC) and the role of nuclear factor-κB (NF-kB) pathway. METHODS BMMSC isolated from normal donors was treated with IL-1β for 1 or 7 days, respectively. Alkaline phosphatase (ALP) and alizarin red(AR) stainings were used to detect the osteogenic differentiation potential of BMMSC. The mRNA expression of EphB4, IGF-1 and OPG in BMMSC was measured by real-time PCR. The immunohistochemistry was employed to measure the expression of bone morphgenetic protein-2(BMP-2) and p-Smad1/5/8 in BMMSC. Furthermore, the Western blot was used for the detection of iκBα and phospho-iκBα (p-ikBα) in IL-1β-treated BMMSC. And the results of IL-1β-treated BMMSC were compared with control group. RESULTS Compared with control group, the osteogenetic potential of IL-1β-treated BMMSC was enhanced, but the pro-osteogenic differentiation effect of IL-1β was remarkedly inhibited in the presence of NF-kB pathway inhibitor PDTC. The total ikBα level of IL-1β-treated BMMSC was lower (P<0.05), and phospho-iκBα (p-iκBα) level was higher (P<0.05). Besides, BMP-2 expression was higher (P<0.05) in the IL-1β-treated BMMSC, however, p-Smad1/5/8 protien level was not significantly different among IL-1β-treated for 1 d, 7 d and control groups (P<0.05). And the mRNA expression levels of IGF-1, EphB4 and OPG in BMMSC were up-regulated after IL-1β treatment (P<0.05). In addition, the osteoblastogenesis of BMMSC treated with IL-1β for 7 days was significantly different from those treated only for 1 day. CONCLUSIONS Prolonging IL-1β treatment can enhance the osteogenetic differentiation of BMMSC more significantly. And this osteogenetic alteration of BMMSC occurs via its NF-κB pathway, but not via BMP-2/Smad pathway.