Recent evidences show that osthole possesses anti-inflammatory properties and protective effects following shock-like states, but the mechanism of these effects remains unknown. The p38 mitogen-activated protein kinase (p38 MAPK) pathway exerts anti-inflammatory effects in injury. The aim of this study was to investigate whether p38 MAPK plays any role in the osthole-mediated attenuation of hepatic injury after trauma-hemorrhage. Male Sprague-Dawley rats underwent trauma-hemorrhage (mean blood pressure maintained at approximately 35-40 mmHg for 90 minutes), followed by fluid resuscitation. During resuscitation, a single dose of osthole (3 mg/kg, intravenously) with and without a p38 MAPK inhibitor SB-203580 (2 mg/kg, intravenously), SB-203580 or vehicle was administered. Plasma alanine aminotransferase (ALT) with aspartate aminotransferase (AST) concentrations and various hepatic parameters were measured (n = 8 rats/group) at 24 hours after resuscitation. The results showed that trauma-hemorrhage increased hepatic myeloperoxidase activity, intercellular adhesion molecule-1 and interleukin-6 levels, and plasma ALT and AST concentrations. These parameters were significantly improved in the osthole-treated rats subjected to trauma-hemorrhage. Osthole treatment also increased hepatic phospho-p38 MAPK expression compared with vehicle-treated trauma-hemorrhaged rats. Co-administration of SB-203580 with osthole abolished the osthole-induced beneficial effects on the above parameters and hepatic injury. These results suggest that the protective effect of osthole administration on alleviation of hepatic injury after trauma-hemorrhage, which is, at least in part, through p38 MAPK-dependent pathway.