Abstract: Objective The acute toxicity of different components in Inonotus obliquus(Fr.) Pilat on mice was studied in order to provide a basis for safe and reasonable medication in clinic. Methods Using classical Methods of acute toxicity tested, the median lethal dose(LD50) of water extraction components and 70% alcohol extraction components of Inonotus obliquus(Fr.) Pilaton mice were tested besides its toxic reaction. Results The higher the dose of water extraction and 70% ethanol extraction components increased, the more obvious the acute toxicity appeared to be, the more the mice died, and the control group showed normal. As to crude drug per kilogram body weight, the LD50 of water extraction components on mice was 17.49g·kg^-1, moreover the 95% confidence limit was 16.36～18.70g·kg^-1; the LD50 of 70% alcohol extraction components was 61.97g·kg ^-1, in addition the 95% confidence limit was 53.73～71.46g·kg ^-1. Conclusion The water extraction components and 70% alcohol extraction components of Inonotus obliquus(Fr.) Pilat had some toxicity, but the working quantity of water extraction components's toxic effect was lower than 70% alcohol extraction components.

Key words: Inonotus Obliquus(Fr.) Pilat , water extraction components, alcohol extraction components, acute toxicity