Objective: To investigate the anti-inflammatory effects and the action mechanism of the fruits of Hovenia dulcis (H. dulcis) in lipopolysaccharide (LPS)-induced mouse macrophage Raw 264.7 cells. Methods: The extract of H. dulcis fruits (EHDF) were extracted with 70% ethanol. Mouse macrophages were treated with different concentrations of EHDF in the presence and absence of LPS (1 μg/mL). To demonstrate the inflammatory mediators including nitric oxide, inducible nitric oxide synthase and cyclooxygenase (COX)-2 expression levels were analyzed by using in vitro assay systems. COX-derived pro-inflammatory cytokines including interleukin-1β, tumor necrosis factor-α andprostaglandin E 2 were determined using ELISA kits. Cell viability, heme oxygenase-1 expression, nuclear factor-kappaB and nuclear factor E2-related factors 2 translocation were also investigated. Results: EHDF potently inhibited the LPS-stimulated nitric oxide, inducible nitric oxide synthase, COX-2, interleukin-1β and tumor necrosis factor-α expression in a dose-dependent manner.EHDF suppressed the phosphorylation of inhibited kappaB-alpha and p65 nuclear translocation. Treatment of macrophage cells with EHDF alone induced the heme oxygenase-1 and nuclear translocation of nuclear factor E2-related factor 2. Conclusions: These results suggest that the ethanol extract of H. dulcis fruit exerts its anti-inflammatory effects by inhibiting inhibited kappaB-alpha phorylation and nuclear translocation of nuclear factor-kappaB.