Ischemia/reperfusion injury of the liver requires the participation of proinflammatory cytokines, chemokines, and adhesion molecules, many of which are regulated by the transcription factor nuclear factor kappaB (NFkappaB). The anti-inflammatory cytokine, interleukin-10 (IL-10) affects inflammatory reactions, at least in part, through inhibitory effects on the transcription factor, NFkappaB. The objective of the current study was to determine whether IL-10 could suppress hepatic ischemia/reperfusion-induced NFkappaB activation and the ensuing inflammatory liver injury. C57BL/6 mice underwent partial hepatic ischemia and reperfusion with or without intravenous injections of recombinant murine IL-10. Hepatic NFkappaB activation was induced in a time-dependent fashion. IL-10 suppressed NFkappaB activation as well as messenger RNA expression of tumor necrosis factor-alpha (TNF-alpha) and macrophage inflammatory protein-2 (MIP-2). In addition, IL-10 reduced serum levels of TNF-alpha and MIP-2. Hepatic neutrophil recruitment, liver edema, and hepatocellular injury were all significantly reduced by IL-10. The data suggest that IL-10 protects against hepatic ischemia/reperfusion injury by suppressing NFkappaB activation and subsequent expression of proinflammatory mediators.