Matrix metalloproteinase-9 (MMP-9) is a secreted type IV collagenase that plays an important role in the remodeling of the extracellular matrix (ECM) and the migration of normal and tumor cells. We have shown that CpG-ODN-induced migration of RAW 264.7 cell is regulated by MMP-9 activity by using tissue inhibitors of MMP-1 (TIMP-1). The MMP-9 gene expression was transcriptionally induced by CpG-ODN in a time-dependent manner. An MMP-9 promoter–reporter was activated by the stimulation of CpG-ODN and ectopical expression of NF-κB transcription factor. Inhibition of NF-κB nuclear localization by co-expression of a mutant IκBα protein blocked the CpG-ODN-induced MMP-9 promoter activation. BMS-345541, an IKK-2 inhibitor also inhibited the expression of MMP-9 gene induced by CpG-ODN. Direct binding of NF-κB protein to the promoter region of the MMP-9 was confirmed by chromatin immunoprecipitation using NF-κB antibody. These results lead us to a conclusion that NF-κB activation is required for MMP-9 gene expression. In summary, our data suggest that NF-κB-dependent expression of MMP-9 in response to CpG-ODN plays an important role in the recruitment of immune cells.