Objective: To study on the compatibility between Rheum palmatum L.

Coptis chinensis Franch. and Scutellaria Georgi in Xiexin decoction. Method: Mice were ig the extractives of the Rheum palmatum L.

Coptis chinensis Franch or Scutellaria Georgi to determine the acute toxicity. Result: The extractives of Rheum palmatum L.or Coptis chinensis Franch had some acute toxicity when they was used alone

and the LD50 of Rheum palmatum L. was 48.92 g/kg

Coptis chinensis Franch was 2 047.9 mg/kg; and the extractives of Scutellaria Georgi had little acute toxicity to mice. But Scutellaria Georgi could significantly decrease the acute toxicity of Coptis chinensis Franch when they were used together. Conclusion: In Xiexin decoction

the acute toxicity of Coptis chinensis Franch may be decreased by Scutellaria Georgi

the mechanism may be related to the reactions between the alkaloid of Coptis chinensis Franch and flavone of Scutellaria Georgi. Perhaps this is the reason why Xiexin Decoction has little acute toxicity on clinical.