Abstract: The essential oil of Gangsong, a light yellow liquid obta. ined by steam distillation of leaves of Baeckea frutescens L., was found to be effective in lowering the elevated SGPT induced by CCl₄, TAA and prednisolone. Prior oral administration of the oil 435 mg/kg twice a day to CCl₄ or TAA-intoxicated mice produced a marked decrease of SGPT and BSP retention. Histological examination showed that hepatic damages of the essential oil pretreated mice were less severe than those of CCl₄ control group. The oil was found to have no direct inhibitory action on SGPT activity in vitro. In addition, the oil was shown to shorten sodium pentobarbitat sleeping time in both normal and CCl₄ intoxicated mice. The data indicate that the essential oil of Gangsong exerts a protective effect against CCl₄, TAA and prednisoione induced hepatic injury in mice. In addition, the essential oil exhibited inhibitory effect on croton oil induced ear inflammation in mice.The toxicity Ofothe essential oil was found to be low, the oral LD₅₀ was found to be 3758±539 mg/kg in mice. No marked toxic effect after administration of the oil to rabbits(687～1030 mg/kg) for 30 days was observed.