Objective:To study acute toxicity of Xidan suspensions in mice.Methods:To measure the LD50 and to observe the response to machinery stimulation and the autonomic activity of the experimental animals when Xidan suspensions is taken orally into the mice.Results:The LD

50

of Xidan suspensions is 148.08g（crude medicinal materials）/kg in the mice by ig.When it is taken orally（ig）into the mice at the dosage of LD

50

or more [180g（crude medicinal materials）/kg]

it is found that the response to machinery stimulation

the autonomic activity the muscle tone and the regulation of balance ability decreased obviously.Conclusion:It is indicated that Xidan suspensions could be toxic to the nervous system of mice.