To comparative study the acute toxicity of four extracts from Xanthii Fructus in mice.Observed the toxic manifestations in mice which were given the four extracts by intragastric administration and calculated the LD50 of the four extracts from Xanthii Fructus.The toxic manifestations of the mice given water extract by intragastric administration were repose, pilo-erection, cyanosis, intention tremor, respiratory inhibition, loss of righting reflex and convulsion . The toxic manifestations of the mice given ethanol extract by intragastric administration were repose, abdominal respiration, intention tremor, intermittent convulsions, incontinence. The LD50 of Xanthii Fructus processed water extract, processed ethanol extract, crude water extract, crude ethanol extract were material drug 155.93, 317.80, 167.6, 275.41 g x kg(-1), respectively.The acute toxicity of water extract is distinctly stronger than that of ethanol extract, but there is no marked distinguish between crude and processed extract.