Objective：Gagam-Gongjin-dan (GGD) is an oriental medicinal prescription composited with Cervi parvum Cornu, Corni Fructus, Angelica Gigantis Radix, Lycii Fructus, Dioscoreae Rhizoma, Citri Pericarpium, Gastrodiae Rihzoma, Agastachis Herba, Cassiae cortex, Scutellariae Radix and Schisandrae Fructus. The purpose of this study was to investigate the effects of GGD extract against acetaminophen (APAP)-induced liver injury in mice. Methods：GGD extract was prepared by extracting with methanol for 7 days. The extract was freeze-dried following filtration through vacuum distillation system. The first, we investigated the antioxidant effects of GGD extract on electronic donating ability (DPPH), nitrite (NO) scavenging and superoxide dismutase (SOD)-like activity. The next, we investigated the possible hepatoprotective effect of GGD extract administration against acetaminophen-induced liver injury in mice. Mice were orally administrated with or without GGD extract of different doses (25-100 mg/kg/day) one times per day for 6 days. After 3 days, APAP was orally applied with a single dose (400 mg/kg). Results：GGD extract increased DPPH, NO and SOD-like activities in dose dependant. APAP treatment significantly increased aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities in plasma. Also, APAP treatment significantly evaluated lipid peroxidation product thiobarbituric reacting substances (TBARS) and depleted some antioxidant enzymes (superoxide dismutase, catalase, d-aminolevulinate dehydratase and gluthathione peroxidase activities) in liver homogenates compared to the control group. However, the orally administration of GGD extract was able to counteract these effects. Histological studies provided supportive evidence for biochemical analysis Conclusions：These results suggest that GGD extract has a potential antioxidant and hepatoprotective effect against APAP-induced liver injury, these properties may contribute to liver disease care.