Gomisin A (Go), a lignan component of shizandra fruits, protects the liver from injury by acetaminophen (AAP). One of its possible mechanisms is supposed to be related to the suppression of lipid peroxidation. Since hepatocyte growth factor (HGF) was reported to prevent hepatotoxin-induced liver damage, we tested HGF as the intermediary of Go effects. Simultaneous analyses of HGF mRNA expression and liver histology in rats were performed at 6 and 24 hr after treatment with AAP, Go or both. HGF mRNA rapidly expressed at 6 hr after Go treatment, while no HGF mRNA was observed at 6 hr after AAP treatment. Induction of HGF mRNA at 24 hr was observed after treatment with AAP or AAP plus Go. Histological findings indicate that massive necrosis and vacuolization in the liver of rats treated with both AAP and Go were reduced in comparison with rats treated with AAP only. These data suggest that Go rapidly induces HGF mRNA through different mechanisms from AAP-induced liver injury.