Objectives : The oriental medicine Jangwonhwan originally described in the Korean medical text, DonguiBogam(amnesia chapter). Recently, a modified formula of Jangwonhwan(LMK02-Jangwonhwan), was shown to reduce -amyloid deposition in the brain of Tg-APPswe/PS1dE9 mouse model for Alzheimer's disease. This experiment aimed to investigate the acute oral toxicity of LMK02 in SD rats by up-and-down procedure determinations. Methods : Quality control of tablet form of LMK02 was established by estimating indicative components, Ginsenoside Rg3 of Red Ginseng and Decursin of Angelicagigas Nakai. The toxicity of LMK02 was investigated in 6 week old, specific pathogen free(SPF), Sprageu-Dawley rats. 3 female rats received 5,000 mg/10 ml/kg of test substance and their death rate, clinical sings, weight changes and autopsy findings had been observed for 2 weeks. Results : Any specific symptoms or death were resulted in this experiment. No significant changes in rats' weight. No significant differences in atopsy. Conclusions : The minimum lethal dose(MLD) of LMK02 for female Sprauge-Dawley rats were more than 5,000mg/kg in this experiment.