This study was aimed to assess the possible toxic effects and to identify the rough safety margin of lemongrass essential oil-water emulsion after single oral administration in mice. In this study, Swiss albino mice placed in nine groups each containing six animals were used. The eight treatment groups were administered with increasing doses of 0.5ml/kg to 4.0ml/kg body weight test doses spaced by 0.5ml/kg. The control group animals were received vehicle. In the two weeks period of acute toxicity evaluation, test doses below 2.5ml/kg body weight does not produce obvious toxic effects. However, some toxicity signs and deaths of mice were recorded at doses higher than 2.5ml/kg body weight. Generally, the lemongrass oil emulsion was not toxic at doses below 2.5ml/kg after single oral administration in mice.