Aim: To examine the possible protective effect of ginsenoside Rg1, an active component of ginseng, on lung injury caused by glutamate in vivo. Methods: The lungs of mice receiving glutamate (0.5 g/kg) and/or ginsenoside Rg1 (0.03 g/kg) via intraperitoneal administration were collected. The indexes of lung wet weight/body weight ratios (LW/BW), lung wet/dry weight ratios (W/D), heart rate (HR),and breathing rate (BR) were determined. The activity of nitric oxide synthase(NOS), xanthine oxidase (XOD), superoxide dismutase (SOD), catalase (CAT), the content of NO, and malondialdehyde in the lung homogenate were measured.Results: Treatment with glutamate for 2 h increased LW/BW, W/D, HR, and BR.These changes were nearly abolished by pretreatment with ginsenoside Rg1 for 30 min before glutamate injection. An analysis of the lung homogenate demon-strated the protective effect as evidenced by the inhibition of NOS (12%) and XOD (50%) inactivity, the enhanced activity of SOD (20%) and CAT (25%).Conclusion: Ginsenoside Rg1 has a potential protective role in lung diseases associated with glutamate toxicity.