The antioxidant and anti-inflammatory protective effects of $eta$-glucan from barley on RAW 264.7 murine macrophage cells induced by lipopolysaccharide (LPS) were examined. The RAW 264.7 murine macrophages were preincubated with various concentrations ($0-200;{mu}g/mL$) of $eta$-glucan and stimulated with LPS to induce oxidative stress and inflammation. The $eta$-glucan treatments were found to reduce thiobarbituric acid-reactive substance (TBARS) accumulation, and enhance glutathione levels and the activities of antioxidative enzymes, including superoxide dismutase (SOD), catalase, glutathione reductase, and glutathione peroxidase (GSH-px) in the LPS-stimulated macrophages as compared to the LPS-only treated cells. Nitric oxide (NO) production was significantly suppressed in a dose-dependent manner (p<0.05) with an $IC_{50}$ of $104;{mu}g/mL$. Further treatment with $eta$-glucan at $200;{mu}g/mL$ suppressed NO production to 2% of the LPS-control, and suppressed the levels of inducible nitric oxide synthase (iNOS) protein and mRNA in a dose-dependent manner. The specific DNA binding activity of nuclear factor ${kappa}B;(NF{kappa}B)$ was significantly suppressed by $eta$-glucan treatment with an $IC_{50}$ of $220;{mu}g/mL$ in a dose-dependent manner. Finally, barley $eta$-glucan ameliorates NO production and iNOS expression through the down-regulation of $NF{kappa}B$ activity, which may be mediated by attenuated oxidative stress in RAW 264.7 macrophages.