Lactobacillus casei 3260 (L. casei 3260) was evaluated in relation to the inflammatory response mediated by lipopolysaccharide (LPS)-induced nuclear factor-${kappa}B$ (NF-${kappa}B$) and cyclooxygenase-2 (COX-2) expression in Raw264.7 macrophage cells. The treatment of Raw264.7 cells with L. casei 3260 significantly inhibited the secretion of tumor necrosis factor-$alpha$ (TNF-$alpha$) and prostaglandins $E_{2};(PGE_{2})$, followed by suppression of COX-2. To clarify the molecular mechanism, the inhibitory effect of L. casei 3260 on the NF-${kappa}B$ signaling pathway was examined based on the luciferase reporter activity. Although the treatment of Raw264.7 cells with L. casei 3260 did not affect the transcriptional activity of NF-${kappa}B$, it did inhibit NF-${kappa}B$ activation, as determined by the cytosolic p65 release and degradation of I-${kappa}B{alpha}$. Therefore, these findings suggest that the suppression of COX-2 through inhibiting the NF-${kappa}B$ activation by LPS may be associated with the antiinflammatory effects of L. casei 3260 on Raw264.7 cells.